# Forum Home Renovation Decking  our first deck - need some advice oiling sanding and black marks

## wends1123

We have just had a new spotted gum deck installed.  We are clueless when it comes to home maintenance stuff.  It was built on steel and unfortunately we had some rain halfway through building, and the exposed areas are covered in black specks.  I know oxalic acid is supposed to be good for getting out black marks from steel.  We were told it is illegal to sell straight oxalic acid now, so we got a Cabot's deck wash that says it contains less than 10% oxalic acid.  Will this be strong enough to get the marks out?  How should we go about washing it?  I am hoping the black marks will come out.  The builder says we will see much worse over the years as the deck ages, but I thought with proper cleaning and oiling it should look reasonable over the years?  Should I be okay with the black marks? 
Also, does the deck have to be sanded?  Again we have no clue how to sand and don't have any sanding tools.  Is it easy to sand?  And will it make a huge difference? 
We are hoping to get it cleaned up over the next couple days, and then oiled as soon as we get a reasonable spell of dry weather. 
Thanks for any information.  We really want to try to take proper care of our deck and maximise how long it lasts. 
Wendy

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## stevoh741

green shed sells oxalyic crystals in containers for about $25. Was it someone trying to sell you deck cleaner that said you can't buy it by any chance? I mix at about 25% which will clear any stain. Scrub with napisan before using the acid.

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## wends1123

> green shed sells oxalyic crystals in containers for about $25. Was it someone trying to sell you deck cleaner that said you can't buy it by any chance? I mix at about 25% which will clear any stain. Scrub with napisan before using the acid.

  Thanks Stevoh741 
Where is the green shed? We are in Sydney.  Do you have any idea where we would be able to get some in Sydney?

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## strangerep

> Where is the green shed? [...]

  "The green shed" or even just "the shed", are oft-used synonyms for "Bunnings". But you should be able to buy oxalic crystals at almost any reasonable-sized hardware store.

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## wends1123

> "The green shed" or even just "the shed", are oft-used synonyms for "Bunnings". But you should be able to buy oxalic crystals at almost any reasonable-sized hardware store.

  That's odd it was at bunnings that we were told it was illegal to sell oxalic acid.  They said they used to sell it.  Anyway, I think our deck issues are a bit bigger now.  The black marks don't seem to be coming out.  Now the builder thinks it is a fungus so we will be applying something called 30 seconds.  I am attaching some photos, does this look like fungus to you?  We have had a lot of rain.  and we have not been able to get any oil or anything down on to it yet as we have not had a break in the rain since it was installed. .

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## stevoh741

I'd be surprised if oxalic acid didn't get it off. Only other option is sanding. Check some of jimj postings in decking threads to find all you need to know about that.

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## jimj

You can try the oxalic acid method which is quite easy. All of the pre-made solutions are based on a 10% concentration of oxalic acid. It can act as a mild brightener and can remove some of the black spotting sometimes but not always. You can try to make a stronger brew as suggested.
However, in looking at the photos I can see that around some of the screws there are small timber burrs standing up. I have seen decks coated without those being removed and IMO it looks fairly woeful. I would sand them off. This can be done quite easy with 80 grit paper and a cork sanding block done by hand.
However, sanding around the screws will leave brighter timber exposed and this may show through the new coating as brighter patches. I can't tell from the photos if the screws are flush with the surface ,slightly raised but they don't appear countersunk with any regularity. 
If they are not countersunk several mm they will in the future prove problematic. All decks look great when first built and coated but most if exposed to the weather will eventually need a freshen up. IMO nothing beats sanding as it brings a new layer of timber to the surface.
OK on this deck I would check out the screw countersink situation and if they are not consistently and uniformly sunk I would have a pleasant chat with the builder and let him know the whole project would be made better with sinking them slightly. Several of the Phillips screws slots looked misshaped. Not sure if they have been slightly scarred during the installation. Most new decks these days are being fixed with a square driven ss decking screw but others smarter than me may comment on Phillips head screws. I hope for your peace of mind they are at the very least SS.
Once the screw issue is resolved I would have it sanded off with 80 grit discs. This is fairly light weight sanding that can be done with a hand held random orbital sander.
Yes it means hands and knees,investing in a 100-125 mm sander and going for it. Or find someone who has the tools and employ them. I understand that all families are on a tight budget . 
This deck is quite dark and sanding it will make it much brighter,remove the black stains,remove the burrs and give you the best starting position prior to coating. 
If you have a look at the photos posted in the thread Porters Cleacote you can see the shot of my hand sanding being done on my knees. The timber had been coated with 1 coat of decking oil but it was still very easy to sand with 80 grit and you can see how much brighter the new timber exposed was. 
good luck  hoping I havn't made it more confusing 
jimj   restore-a-deck.com.au

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## strangerep

> That's odd it was at bunnings that we were told it was illegal to sell oxalic acid.  They said they used to sell it.

  IMHO, there's a fair proportion of BS in what they told you. I saw containers of crystalline Oxalic acid on the shelf at Mitre10 (Mona Vale) only a few days ago. Also, take a look at this link:  Wood Restoration 
(in particular, the bit where he mentions how oxalic is available at Bunnings under a different name). 
But I reckon you should try to get oxalic in crystalline form. Cheaper that way, and you'll need to make up quite a strong solution.   

> Anyway, I think our deck issues are a bit bigger now.  The black marks don't seem to be coming out.

  They do look like mould to me. 
I recently gave my deck a bejeezus cleaning in preparation for re-oiling with Cutek CD-50. My procedure now is this: 
1) Apply strong Napisan (sodium percarbonate) by 12mm roller. I.e., make it up in a rectangular bucket into which the roller can fit. Keep the areas lightly moist by re-wetting with a spray hose
those areas which start to dry before you finish -- the idea is to keep the Napisan active for longer.
Then hose it off very thoroughly. Wait 10-15 minutes, and re-hose. Repeat this until it no longer foams. Clean your roller. 
2) Apply strong chlorine bleach (e.g., Bunnings outdoor cleaner, or White King concentrate, diluted down). Apply with roller as above. [Warning: this step is controversial -- chlorine if often discouraged on timber. But I've been doing it every couple of years now, and the deck is still ok. My humble opinion based on my own experience is that it's acceptable to do this -- a timber deck is unlikely to last more than a few decades in good condition anyway.] As in step-1, keep lightly re-wetting any areas that dry before you finish, then give it the same multiple hosing treatment. 
3) Apply strong oxalic acid, pretty much by the same method as above. I was so impressed by how much brighter the timber appeared after this step, that I gave a 2nd treatment of oxalic. Apply by the same method as above, and the same intense repeated hosings. By this time, your 12mm roller will probably be reduced to maybe 6mm, so discard it. 
At this point, you really need to get every last trace of oxalic out of the timber, else it could bleach the colour in whatever oil you apply. 
In all of the above, the solutions need to be STRONG. E.g., a mug of Napisan/Oxalic in 1/3rd of a bucket of very HOT water. I even added some boiling water from the kettle to make it hotter than what comes out of a hot water tap. (Remember that it will cool down a lot while you're applying, so don't make up too much to start with -- maybe a little more boiling water halfway through to warm it up.) 
Others may well disagree with such strong treatments. But I can say that in the end, after 2 applications of Cutek CD-50, my deck looks far better than I'd have ever thought mere cleaning could achieve. (I couldn't face the effort of sanding it this time.) 
Also remember that bejeezus rinsing after bejeezus cleaning is very important.   

> We have had a lot of rain.

  It's actually better if you can do some the cleaning steps above, and then let the rain do some of the rinsing....

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## wends1123

Thanks for the responses.  I think we will invest in a hand sander.  I had a look at the screws Jimj, and you are right, some of them seem to be right up at the level of the timber.  I know he had predrilled with the intention of countersinking the screws, but it seems to be fairly inconsistently done.  So we will bring that up with him.   
Is it common for timber to go moldy so quickly?  And should we be concerned about the underside of the timber?   
A deck cleaner with oxalic acid was used on a portion of the boards in the picture, which had oxalic acid did nothing for the stains.  You can see a line where the cleaned timber was bleached by the deck wash without lifting the black marks.  Actually the timber looks pretty rubbish where the cleaner was used, and I wonder if the concentration was too much, as it looks a bit whitish grey.   
I am sure we will get there eventually, but it is a bit disheartening to have so much mold before we have even gotten to sit out and enjoy our first beverage on it.

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## wends1123

After reading this post I was just discussing the fact that the screws are not properly countersunk, and I joked at least they are stainless steel, and he said, no they are not.  The builder told him they were not stainless steel, and my husband asked, are they the screws for the job?  And the builder said yes, now we are looking at the box that the screws came in, and I see a caution on it saying they are not recommended for fixing timber to steel!  The bearers and joists of our deck is galvanized steel.  the screws are class 3 galvanized steel.  We originally were going to go with aluminium for the bearers and joists, but the builder said he found galvanized steel ones, and they would be a lot cheaper and last for ages and ages.  Is this true?  Have we been misled?  The deck was not cheap, but we figured better to pay more and have something that would last.  Please any information would be greatly appreciated

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## jimj

No doubt others on the forum that are a whole lot smarter than me will comment,guide,suggest etc about the screws. There are 2 sponsors of the decking forum. Scrooz offers very good advice and doesn;t force anyone to purchase from him. I do know that it doesn't take that much effort to drill consistent depth countersunk holes so that every screw is   cosistently secured several mm below the surface. All decks look great when first built but if they are exposed to the weather eventually they will need restoring and although chemicals can give some restoration-preperation improvement there will come a time that sanding is only solution. If products like DWD,sikkens cetol deck,HLS, Flood Spa& Deck the chemicals WON"T work. They require the use of a stripper to dissolve the film that is there and the mess that is generated is not a lot of fun. 
I would have the screw issue resolved before anything else. Is there a contract/written detailed quote that specifies exactly what is going to be supplied and done. If it says countersunk and they aren't you may have to discuss this and reach a solution. I hope for your sake that you reach a happy conclusion. 
Mould is a difficult issue. It will sand off fairly easy and you won't see the spores but it doesn't mean they are all gone. Nothing seems to be the best solution. I do add Flood VC175 which is a mould inhibitor-retardant. Will it stop any more mould from showing up? Absolutely not! Does it help. Yes I would say it reduces it down by around 50% which for the $20.00/20 litres of coating product it isn't too  bad.
Another contributor of mould is the amount of vegetation that is in close proximity of the deck. I can't tell from the photos if that is the case but it does play a factor. another major contributor to mould is if the coating product oil is derived from a plant or animal. The mould will feed off the organic oil.
If you had a look at the photos in the thread Porters Clearcote those screws were countersunk by the builder evenly but I still had pencil lines, burrs standing up and some mould to sand off on the outside exposed timber. It sanded easily. 
If you are going to sand dust extraction can be an issue. Most of the cheaper units extraction is poor. If you can have someone with a vacuum hose working in conjunction with the sander it can help keep the dust issue minimised. Sanding over the dust created reduces the ability for the abrasives to do the best and blocks your vision .
I hope something here might help. 
jimj   www.restore-a-deck.com.au

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## wends1123

We had a carpenter friend who lives nearby take a look at the deck.  He said he would definitely get the screws fixed for the safety of the kids walking on the deck if nothing else.  So we will bring that up with the builder.  He also said the black marks do look like they are from a metal reaction.  The builder was grinding the steel joists and bearers near the deck and the metal bits would have gotten everywhere.  He was nearly positive that it is not a fungus.   
He suggested the issue with the screws might be because the joists used are only about a 3ml gauge, and they might not have had enough grip to pull down far enough.  So I am not sure how this issue will be resolved. 
So the deck cleaner we used bleached the timber without even touching the black marks, does this mean we have no hope of getting the marks out?  or will a strong concentration of oxalic acid still might get it out.  Is this just our bad luck?  or is the builder in some way responsible for grinding steel all over the deck?  Certainly wishing we had splashed out a bit more for the aluminium joists now. 
Thanks for all the advice so far.

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## jimj

On that last Clearcote deck I had some fine metal elements from the fellow who was repairing the shutter hinges. I was able to sand off the black stain. Oxalic acid is also used to remove blackened steel marks from timber. So in this case I think it is just attempting different approaches. Unfortunately a raw timber deck can be messed up from a lot of issues before coating like,grease,wine,steel nails,shavings etc.
 Another reason why I recommend to get it coated asap once the construction is finished.
I sincerely hope that your new deck and the cost of it can conclude happily . If the screws are proud enough to snag bare feet then they really need addressing. 
jimj

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## stevoh741

> That's odd it was at bunnings that we were told it was illegal to sell oxalic acid.  They said they used to sell it.

  The person you spoke to doesn't know what they're talking about. I was in the gay green shed today and they do sell it. It is called diggers stain and deck cleaner and is 100% oxalic acid.

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## wends1123

> The person you spoke to doesn't know what they're talking about. I was in the gay green shed today and they do sell it. It is called diggers stain and deck cleaner and is 100% oxalic acid.

  That's good to know, we will get some this weekend. 
Should that work on stains from sap too?  The builder was convinced the black marks are from fungus and not steel shavings, so we were a bit concerned that there might be mould growing on the bottom of the boards too.  He took a sample board to the timber yard where he bought it, and they said it was definitely not fungus.  They said it also was the wrong colour to be marks from steel, but asked if we have any gum trees nearby.  There is one a couple of houses up from us.  Anyway, they said it was most likely staining from sap from a tree.  So will the oxalic acid work well on that?  Is it common for sap to cause extensive staining on a newly laid deck or do we just have bad luck?

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## jimj

Not sure if you have had a look at the porters clear cote thread. There are some photos of a deck that I hand sanded 80 grit quite easily. Have a look at the image 2637 and the next ones. You can see a similar photo as to what yours look like. 
Not trying to pick on the timber yard or yourbuilder but what you are seeing on spotted gum prior to coating and during the building stage is fairly common. 
Why not get a sheet of 60 grit and a small cork sanding block and do a test. Finish it off with 80 and I think you will see the black come off easily,the timber brighten easily. If that works invest in a hand sander. It will also remove the burrs from around the screw holes.
I don't think your unlucky and I really can't see how a tree several houses away can be blamed for sap on your deck. I have never encountered sap from a tree .I would agree that when Eucalypts are in flower you can get a lot of the small flower pats on your deck when it is a little breezy. 
As far as what is under the deck. If you can't get under the deck then it will always be an unknown-inseen again area. If youi can see under the deck I would just paint it off with a dark colour with 3 coats of acyrlic paint. 
Has there been any resolution with the builder and the screws? 
jimj

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## wends1123

Thanks for the additional advice jimj.  I picked up some sandpaper today and gave it a try on some of the stained boards that were not used in the deck. Sanding took up about 80% of the marks. Some bits seem to have penetrated the wood a bit deeper, but it is not very noticeable.  So I am very pleased with the result.  Actually, sanding the deck will be a bit of a trick as we did not end up with a fully resolved screw issue.  The builder reckoned we were being unreasonable and that  90% of the screws were perfect which is pretty good.  He did spend a bit of time redoing some, but it seems that there are about 50-60% properly countersunk and the rest are a combination of flush or above the surface of the timber.  We might pay someone else to come in and touch up the screws for us, our only concern is that it is probably difficult to screw into the joists the builder selected otherwise he would have countersunk them himself.   
We are keen to get the deck sanded and get a coat of oil down before any more dramas arise, so we will see.   
Are there any brands or types of hand sanders that would be appropriate for us?  And is it pretty easy to sand without messing it up?  After we sand should we give the deck a wash?  I thought maybe a napisan followed by an oxalic acid wash might take up some of the last black marks after the sanding.  We just picked up some Australis natural oil at the local paint shop because we wanted to get something down quickly.  Will it be possible to switch to a different brand without any dramas when it comes time to re oil?  Do you know anything about that brand or if it is any good?  I read good things about Cutek, but we would have to order it online to get it in Sydney, and I wasnt sure which colour to pick.   
Are there any hand sanders that can also be used as buffers?  We have cypress pines floors in our house and they are finished with Synteko Natural, and I thought if they made a machine that sands and buffs it might be useful to us.  I am not sure if they are totally different types of machines that just look a bit similar though.  
Thanks again for all your help.  I am confident that we will get the timber looking pretty good now with a bit of work, so I am down to one concern, getting the screws in deep enough to allow for sanding. . . we will get there eventually.

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## jimj

Sounds as if you are working through the issues. I don't think it is unreasonable to have 100% of the screws countersunk. At least the sanding will remove the burrs. I am not sure how many m2 of deck there is. You may wind up having to hand sand this with a electric orbital sander. It will take a little time but thats what it is. 
There are many sanders on the market and I can't advise as to which will give the best result for the $ to buy. Unless you want to go to the high end of costs. You may find your local hire place may have a quality orbital hand sander for hire.
The one I use is close to 900.00 to buy which I would think is way overkill for your needs. 
In respect for which coating. That is a another topic that will lead to more opinion,conjecture &preference. some folks will only use oil based and others water. the sun is the greatest degrader. Some products handle the sun better than others. Other products look better than others,Some products are easier to apply than others then there is smell,clean up,drying time,recoating time etc. 
I would suggest looking through the archives and try to make your decision based on the comments that seem to suit you. 
best of luck 
jimj   restore-a-deck.com.au

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## blindjoe

Hi All 
First time commenter, recent convert. I am having similar problems with black spots on my deck - build in May in Sydney. Two days after laying the spotted gum decking boards we had a some fairly heavy rain, which we worked through, thus trudging lots of mud, sawdust, leaves and grass over the deck which sat for the night. The next day was very windy and the deck dried quickly but many black spots appeared. Some areas were far worse than others - in particular the steps which had attracted the most muck. We worked under a market umbrella in metal stand. There was a big square black stain where it sat overnight. My chippy had no idea what caused it and since then I have been hitting the forums and talking to various experts. I happen to know a eucalyptus expert at CSIRO - "hmmm, looks like a metal reaction... then again could be fungus". I think there could be a PhD in this.   
The first photo is the sort of random black dots I have all over the place. The second picture is black that emerged around a spotted gum wood plug in the top rail after subsequent heavy rain. The 3rd is black that is definitely related to sanding metal fragments from the top of a screw that wasn't properly countersunk. The 4th is the step which was near black before I hit it with a belt sander. So I have all these potential suspects: reaction to metal - definite for the umbrella and screw stains but there was no metal working going on; fungus - some spots look like they could be; tannins leaching - maybe for the top rail and for some black marks that follow the grain. 
So I have tried napisan in spots and it didn't seem effective. I have sanded some of the black out but that doesn't solve the problem but only improves things a bit. The big rectangular stain from the umbrella just disappeared over the next rainy month. The black spots on the top rail will not budge. Belt sanding did less than I would have expected and I don't intend to do much more of it but my orbital sander is an infuriating $15 piece of rubbish. I will try oxalic acid next.  
I'm very interested to see how your treatments work  
Blind Joe

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## jimj

Welcome to the forum. Sifting through the archives will reveal a lot of valuable information. 
1. Any steel item left in contact with damp wood can leave some black deposit-staining. Oxalic acid based solutions can have a bleaching effect on wood and can sometimes bleach out the metal stains.
2. It is not uncommon with spotted gum left in the weather to develop black spots even when no steel-metal has been in contact. It is often black mould. 
I encounter both often on decks. Most people don't like the idea of sanding as it is seen as just too hard. Well after having tried the chemical preperation for quite some time and being less than happy with the result I shifted to sanding.
It will remove the fine surface layer and generally all the black spotting-marks are gone. This deck would sand off easily with 60-80 grit. The problem is the cheaper orbital sanders can't handle the downward pressure that is required to sand. Hand held belt sanders can't be run across the grain where orbital can. 
I guess with a 15.00 sander you are being severely challenged. Generally a hand held orbital needs over 400 watts of grunt. There are not too many of these.  I have your normal makita orbital with 160 watts and I wouldn't even take it the job site for any sanding what so ever.Mine workhorse is a handheld orbital and 720 watts with excellent dust extraction. Sure they are pricey but it can easily handle the downward pressure required. 
My vote is to sand,get a new exposed timber surface and get it coated asap once sanding is done. 
good luck 
jimj     restore-a-deck.com.au

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## wends1123

Hi Blindjoe 
Sorry to hear you are having a similar problem to us.  I have found a deck restoration company, and we are going to have our screws countersunk and have the deck sanded and then coated with Cutek CD50.  From the small sample bit we sanded, it looks like it is going to come up pretty well. 
It is a bit of a mystery what it actually is.  We choose spotted gum because it is a durable timber and has a beautiful grain, but no one mentioned its proclivity for black marking.  But then I suppose all timbers are susceptible to marking.   
Good luck with finding a solution to your deck problems.  Your photos do look quite similar to what we are experiencing.  I will let you know how we go with our sanding. 
Thanks again Jimj for all of your time answering posts.  It really is helpful and appreciated.

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## jimj

Wends
 Good to hear you are going to the extra effort to turn this project around. I sympathise with your predicament regarding the screw installation. It doesn't take any more effort to secure them below the timber. nearly all decks if left in the weather will eventually need refinishing . It may be a number of years  later but it will finally reach that point.
I am guessing that your builder has left you to sort this out and has moved on. Sorry about the extra costs to you. I know that when it is all completed you will be happy. 
I am currently restoring a deck that had SS square driven decking screws installed with 80% of them flush or proud. I have had to withdraw,countersink and install 3500 screws before I began sanding. Its been mind numbing tedious , all sanding of the flaking Sikkens  is completed and 4 coats of Spa& Deck applied.  Hopefully will be done today. 
I am sure the forum will look forward to hearing your thoughts on completion
PS  Thanks for the kind words 
jimj    restore-a-deck.com.au

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## blindjoe

Hi 
Thanks for the advice JimJ. Wends - I have a theory about the black spots.  
First off my deck was screwed and they are in nice clean straight lines. The holes in the decking were pre-drilled but they not countersunk and the treated pine joists were not drilled with pilot holes. For the most part the deck was very well constructed, but clearly these cut-corners are costing me. The screws self-countersunk which means that I have timber burrs to deal with. Fortunately 99/100 screws were countersunk and to a reasonable approximation of the same depth. I started fixing up the 1/100 and discovered that nearly all of them had snapped - half way down the shaft about where the screw would be a few mm into the joists. I had some left over supply from the job and looked at the box - chipboard screws. My builder, who happens to be a good friend of mine, said that he has used these for several decks with no problems. Well this is a fairly serious problem because the threads of these snapped screws were starting to corrode. I had a close a look and could see the beginnings of rust on many of the heads as well. I am going to have to change the screws - very annoying. My builder friend is from the country and came up to Sydney to build my deck - perhaps these screws are good for years out in the dry inland. A km or so from the beach and they didn't last a month. 
I bought 1250 marine grade stainless screws online ($148/1000) and I set about changing them today. Between 5-10% of the chipboard screws had snapped. About 1 in 3 of these would not easily come out and I would have to lever them out while slowly drilling. So far about 1 in a 100 won't come out at all and the heads are starting to shred. I am drilling out using a Makita cordless set on hammer drill as that seems to be far more effective than screw or drill modes. With a bit of experimentation it seems most effective to hit each hole with a countersink bit which cleans most of the burrs and allows me to drive the screws in using the screw setting and 8 times out of 10 when the clutch engages the screw is the right depth. In the other 2/10 I have to go to drill setting and do another rotation or so.  
But for the relationship with the black spots. These philips head chip board screws are really very prone to shredding, especially when the driver bit is starting to wear. The tiny metal fragments land on the timber in a fairly random sort of pattern similar to the spotting. I need to run an experiment to confirm my hypothesis - shred a screw on a off-cut and then sprinkle water on it and see if it turns black - but I am fairly confident that the random black spotting is caused, in my case, by shredded screw heads. I am hoping the SS screws don't yield the same reaction in the timber but I made sure to sweep the section of the deck i worked on very thoroughly. The SS screws seem to be a lot less prone to shredding but I have damaged maybe 5-10% of the ones I have driven but only a few are seriously damaged. After changing all the screws in a section then I go over the area with my new random orbital sander - about $150 this time, 350w Bosch - most powerful one in stock at bunnings (not saying much - 10 display items and only 4 models in stock!). I worked thoroughly over a few of the black spotted areas with fairly good results.  
Wends - given the uneven countersink and the philips head it seems likely that some of those screw heads would have shredded. 
I should sub-contract this job out - my baby soft office worker hands are torn to shreds - but I'm going to do it myself. 
Questions - 
Any tips about getting the difficult screws out? 
Will stainless screws react with the timber? 
How deep should I countersink? 
And when I sand the timber burrs are wiped clean in a few seconds but I am left with a feathered pattern in the timber. It seems if I work on the area for about 100 times longer than I would like to I can sand that away. Is there any other solution to clean the burrs away? Should I care about the feathering or just imagine a year has passed and the deck is all scratched and weathered anyway?

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## shauck

For screw removal when the screw is damaged   Grabit Damaged Screw Remover. #8520P

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## jimj

Blindjoe, 
Thanks for sharing your project and it sounds as if you have worked out what some of the issues are. Looks like you are getting on top of rectifying and at least you havn't coated yet so it can be turned around.
. Removing stuffed screws can be easy or next to impossible. There are a number of variables that can influence this. 
1. I have had some reasonable success removing damaged screws with a {GRABIT damaged screw remover kit} from memory I think I paid around $50 for it. You can probably find it on Google with illustrations and instructions. The kit has helped remove some screws but not everyone.
I am sure others on the forum will have other helpful suggestions. Stainless screws are the norm with outdoor decking.  
2.Sounds as if you have invested in a much better sander. I had a look at the photos and I am not exactly certain what you mean by feathering. If  you mean it looks a little lighter in colour around the holes. If that is the case it shows the brighter timber underneath the weathered layer on top. If that is the case you need to decide "should I sand the entire deck to bring this brightness up over the entire deck" personally I would. As the the brighter the timber prior to coating the better appearance after coating.
If you mean the feathering is from a small amount of timber tearout of the burrs surrounding the hole,then just move on and keep sanding. The small tearouts will not be that big of deal once the entire project is finished. 
3. I like to countersink to a depth of 2-3mm. Others will have their own preferences. 
OK can't do anything much about the baby bum hands. However, I would recommend a well stocked beer fridge . A professional consultation at the end of the day with the fridge can dull the pain. 
jimj  restore-a-deck

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## blindjoe

Maybe instead of feathering I should have said ripples. The pattern in the board that looks like a set after set of gentle waves. Prior to sanding this wan't there and then with a gentle sand there is this pattern. After a couple solid minutes of sanding it is gone. I had the same issue with the el cheapo sander and the better sander. I also had some fairly pronounced 'ripple' pattern in my top rail, which is a solid bit of spotted gum which I imagine came from the thicknesser at the mill (as well as various gouges, but that is another tedious story that involved a lot of belt sanding.) 
I guess I will oil a section and see if the rippled disappear or become more prominant and work out whether i like the way it looks or not.  
Thanks for the tips.

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## stevoh741

the ripples are just planer marks

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## jimj

Thanks Stevoh
Was trying to get my brain into gear with the ocean ripples. Great description of timber Blindjoe. You said you didn't see it prior to sanding . Probably due to the dirty timber after building. I would think the marks would be mainly at the ends of the boards where they went through the planer. I wouldn't think it would be that difficult to sand them out if they bother you. I see the marks often on decks that I visit as not many of them were ever sanded after construction was finished. 
I guess it will come down to what bothers you and what doesn't. At least you are working through the screw issue. 
Best of luck 
jimj

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## blindjoe

Hi All 
Wends - based on your comment about Cutek I looked them up. I was going to use Feast Watson natural decking oil because I have used it other other projects and have a near full tin. On the old deck that this one replaced I was using Aquadeck - very happy with the longevity but not too happy with the appearance. I think it looked ok on the Merbau of the old deck but I think it will ruin the grain and colour variability of the spotted gum. I tested the FW and it I was happy but I am interested in the Cutek product - have you found a stockist in Sydney or this is from the deck restoration company? 
While I was looking at the Cutek website I came across this info on stains on their site which ends with a recommendation for their product called Cutek proclean WAO stain remover specifically for iron stains. Does anyone know about this product?  *"Iron Stain* 
Iron stain, is an unsightly blueblack or gray discoloration that is often incorrectly described as "mould" because of its frequently "spotty" appearance. Iron stain can occur on nearly all woods, however some timbers are particularly prone to iron stain because they contain large amounts of tannin-like extractives. The discolouration is usually caused by a chemical reaction between extractives and iron content in steel products, such as nails, screws, and other fasteners." _(and it then goes on for a quite a while - link is below)_ *Marks Or Stains 
CUTEK Proclean WAO Stain RemoverCUTEK Proclean WAO Stain Remover was developed because exterior wood surfaces including structures, shingle roofs, decks, and cladding become discoloured from dirt and general weathering and greying. CUTEK Proclean WAO Stain Remover counteracts the weathering process by eliminating years of discoloration and fungus from all species of timber. It cleans, brightens and restores wood surfaces back to the appearance of new timber. Additionally, it is exceptional at removing stubborn stains such as tannin stains, resin stains, fungal and algae stains, green CCA stains, oil and grease stains, surface greying and many other chemical stains and discolourations that may destroy the natural beauty of wood.  *   And yes, I have a beer going while I am doing all the deck work. And the second couple hundred screws went a lot quicker than the first. 
Cheers
Blindjoe

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## jimj

I think you will find the WAO's main active ingredient is Oxalic acid. This ingredient is the main one found in most timber cleaners. Oxalic acid has the ability to slightly brighten timber and sometmes remove black metal stains.  
jimj

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## decland

Black marks on my partially laid deck are definitely caused by metal particles or the galvanized or zinc coating or whatever it is on steel frame work. yesterday I laid my first six planks of northern box decking on steel bearers using galvanised counter sunk self taping winged screws. some of the screws would not drill into the steel so i predrilled and some metal filings were left on top of the decking. It rained last night and i noticed stains same as in photos in this discussion where metal shavings had been left. tried to remove the stains even though they were new with no luck. even if you dont pre drill some metal particles still come out of hole and spread around the drilled hole and under the screw head which may cause staining around screw. have decided to blow of newly laid boards with compressed air.  :Annoyed: Will galvanized screws stain this decking :Confused:

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## wends1123

Feeling pretty disappointed with our deck at the moment. 
The work on countersinking the screws has begun, but in the parts of the deck that are exposed, about 30% of the screws have snapped, not sure what is going to be done about that, 30% just cannot be removed, and 30 % have been countersunk and replaced, and look really good.   
I wish the original builder had told us that it is not recommended to screw timber to metal.  We thought we were getting a better deck because we wouldn't have to worry about timber underneath rotting out, but the deck is only a couple months old, and it has all kinds of problems!  What is the point in having a screwed deck if you can't remove the screws?  Really wishing we had gone with timber underneath!  It would have been cheaper too.  Anyway, enough of a rant, if we ever get to the sanding and finishing stage, I will post a picture.  The timber itself is really beautiful, and I think it will come up really well when it is sanded and covered with a couple of coats of Cutek CD50.

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## stevoh741

> Feeling pretty disappointed with our deck at the moment. 
> The work on countersinking the screws has begun, but in the parts of the deck that are exposed, about 30% of the screws have snapped, not sure what is going to be done about that, 30% just cannot be removed, and 30 % have been countersunk and replaced, and look really good.   
> I wish the original builder had told us that it is not recommended to screw timber to metal.  We thought we were getting a better deck because we wouldn't have to worry about timber underneath rotting out, but the deck is only a couple months old, and it has all kinds of problems!  What is the point in having a screwed deck if you can't remove the screws?  Really wishing we had gone with timber underneath!  It would have been cheaper too.  Anyway, enough of a rant, if we ever get to the sanding and finishing stage, I will post a picture.  The timber itself is really beautiful, and I think it will come up really well when it is sanded and covered with a couple of coats of Cutek CD50.

  If its any consolation SS screws shear of out of timber too

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## jimj

I truly sympathise with your situation. You have outlayed a lot of $ and are still dealing with issues that could have ben avoided. I wish you luck in reaching a point that will finally allow you to both feel hapy with your deck and allow you to use it in the way that you want. 
Looking forward to the finally finished photos 
jimj

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## wends1123

I will post some pictures soon.  The sanding worked really well to get the black marks out.  As I mentioned before, many of the screws sheared as they were being removed, and some of the screws just couldnt be removed at all.  For the screws that sheared, the builders just put new screws in at an angle.  And while it doesnt look fantastic if you look closely, most people probably wouldnt really notice, as they are probably not scrutinising the screws like I am.  The ones that couldnt be removed got sanded, and since they are galvanised they just had to be painted with some galvanised paint.   
We went with Cutek cd50 for the oil.  We are very pleased with the result.  It took ages for the second coat to dry, about 2 weeks till it really felt dry, but it was a cold spell.  We will try to do our maintenance coats in really hot weather.  The colour has a slight orangey tint to it, but I still think it looks good.   
Thanks for all your support and help through this process jimj.  It is nice that we will be able to enjoy the spring weather out on our new deck.  The people we hired to sort it out for us really seemed to know their stuff and cared how their work came out.   
I will try to get some photos up over the next couple days.

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## jimj

Absolutely  wonderful to hear that you have solved your decking issues and nice to hear you found someone who cared to turn it around for you.
I am sure that al of those who have followed your thread will be delighted. We look forward to seeing the photos. It will help al of those who follow this forum 
jimj  restore-a-deck :Biggrin:

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## wends1123

as promised here are a few photos of how the deck turned out.  So it is spotted gum sanded and finished in Cutek.  As I mentioned above it did come out slightly orangy, but the grain still looks amazing, and all the black spots are gone  :Smilie:  
I will post again in the future to let people know how the Cutek performs for us.  But for now, I am happily enjoying our deck.  Good luck to everyone else with black mark issues.  I hope you get yours sorted.

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## jimj

Well your perserverance to turn this around has paid off. Enjoy your deck and those of us that follow the forum will look forward to hearing  from you how the cutek performed 
jimj

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## shauck

Can I ask, what tint was used?

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## barney118

I used these S/S screws for screwing my deck boards to steel, I couldn't find any others at this price/volume. I used a smartbit to countersink into the timber and pre drilled through the steel with the bit, these are self drilling but with timber you need to pre drill otherwise the screw bites into the timber and will split it. eBay Australia: Buy new & used fashion, electronics & home d

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