# Forum Home Renovation Painting  Oil or water based undercoat?

## Marc

I sent my daughter to buy paint with precise instructions to buy oil based undercoat and water based exterior paint Dulux brand.
She came back with Taubmans 3in1 acrylic undercoat and exterior paint from Taubmans. 
Now I always buy dulux weathershield or the other one from wattyl, never used Taubmans before, plus I always use oil based undercoat, however I am no painter and the desk jokey told her that this two products are "better". 
Do I go and change them or are they just as good?

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## phild01

Generally I have found water based primers far superior to oil based but they don't seal tannins in.  Th 3 in 1 is the only Taubmans paint I would buy too.  You haven't mentioned the timber though. 
Was it Bunnings because they push Taubmans?

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## ringtail

Personally I would always go oil based. No way can an acrylic primer lock protective resin into the timber simply because it has no resin to give. Oil based is getting harder to find these days and most have gone to a quick dry formula - sign of the times, rushed rubbish workmanship. On the quick dry stuff I now chuck some diesel into it. Mixes in well, still dries quickly ( not as quick) but most importantly, flows better and actually penetrates the timber

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## Marc

Sorry should have said it was for new treated pine, exterior and horizontal not vertical. Mm, one acrylic the other oil. yes what she brought was 3/1 taubmans undercoat and wall cover paint for exterior water based paint.

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## phild01

The primer will be fine.  I don't like oil based unless the timber demands it.  I find the oi based primers don't last the distance and break down many years down the track (exterior).
Like you I prefer w/shield or Wattyl S/guard.  I've used Taubmans exterior paints before, including Endure and they seem thin to me.

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## mudbrick

Is the wall paint endure or just an everyday version?
if it's in a full sun position and going on something you want to last I'd only bother using one of the big names, Endure, solaguard, weather shield etc.
I used a hardware store brand outdoor acrylic on some roof fascia and it wore off in 5 years, so fast I still had the original tin in the garage claiming to have a 10 year warranty!

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## Marc

It is endure

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## justonething

> Personally I would always go oil based. No way can an acrylic primer lock protective resin into the timber simply because it has no resin to give. Oil based is getting harder to find these days and most have gone to a quick dry formula - sign of the times, rushed rubbish workmanship. On the quick dry stuff I now chuck some diesel into it. Mixes in well, still dries quickly ( not as quick) but most importantly, flows better and actually penetrates the timber

  What type of quick dry do you add diesel? is the quick dry water based or something else?

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## mudbrick

One hopes that would be fine, does the endure tin say to use the 3in1 undercoat or something different ?

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## Marc

Like most water based exterior paint it says it does not need undercoat, but from experience it is way better to use undercoat.

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## ringtail

Quick dry oil based + diesel. After all, if one reads the label on a bottle of penetrol ( oil based additive) it clearly says it contains petroleum distilates ( diesel) so I figured it can't hurt and so far so good

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## Marc

Alkyd paints are derived from a process starting from vegetable oils to produce drying and non drying resins diluted in solvents. This is the binder and the paint manufacturer adds pigments fillers and solvents to this base plus a string of other stuff that is the realm of black magic. Diesel mixes well with most of the oil based components and that is why you can add it to the paint. 
Being a mixture of hydrocarbons that do not dry by the usual oxidation process the vegetable oils are subject to, it will slow down the drying process the manufacturer has so carefully tuned in the paint.  
If that is an improvement or not, I can not say, It probably depends from the paint in question. By making it less viscous it may improve the so called penetration in the wood, however as previously discussed, said penetration is a bit of a myth and only some solvents or water are able to get into the wood further than a few hundred of a mil.

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## Marc

To illustrate a bit my non existing experience with painting, I once had to paint the bottom side of yellow tongue that was the floor of an attic and the ceiling of the room below. I started with a coat of the same paint I was using for the walls, some water based of alleged great qualities. The paint disappeared sucked in by the particle board leaving almost no trace of the colour. I proceeded to buy water based undercoat and gave it 3 coats with the same result. the wood particles kept on showing up. i then bought oil based undercoat and after 2 more coats I finally had a surface that would take the wall paint and cover to an acceptable level. I have no idea if the oil based undercoat would have done the job by itself or if it only worked because it had already 3 coats of water based under it.

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## Marc

So at the end I used the water based my daughter got me. I cut all the timber to final leanght and had also to plane a corner to fit a weld that is in the way. 
I first applied one coat of a timber preservative to all cuts. It is based on Copper Naphthenate. it tintes the timber the same color as the treatment. Cool, and it stinks to the heavens.  
The 3in1 undercoat is as thick as glue and it absolutely sticks to anything. I can not predict results but so far this undercoat seems to be the ticket. 
I read a few articles about water based versus oil based paints and most seem to be a bit outdated, stating that oil paint is more durable than water based. When water based paints have improved in leaps and bounds, oil based have gone backwards due to environmental concerns real or imaginary, and the same goes for undercoat.
I used to manufacture glue and the resin reps use to talk to us about paint making until the cows came home. It does not mean I know how to paint or what to use, but I have an idea of what goes in the paint and I think the days of oil based are numbered. 
Lets hope it is for the best.  After all, both have resins that polymerise to form a film, just different solvents or dispersant.

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## Marc

I thought I have to write a followup in fairness to the good information provided here and the misinformation I gobbled up in ignorance. 
This is what happened. The "oh so good" water based undercoat 3 in1 from Taubmans did stick like glue ... apparently ... Because of the high number and size of the timber I had to paint I had them standing up against a wall away from each other but with the tip touching in an ever increasing angle. This way I could fit the lot in a small space. 
I left it to dry and came back the next week. When I started to pull them apart to give it the second coat, the oh so good water based undercoat peeled off at the point of contact as I was separating the pieces, showing the green treatment of the pine. Almost nil adherence! I could pull the strips of undercoat and they would come off in long strips with minimal effort. Absolute crap! 
So ... I took to them with a mask and a 4" belt sander 40 grit and so I blew  $100 to the wind, literally.
After using the blower to clean up all the dust, I bought what I initially ordered and did not get thanks to some moron at Bunnings and my own laziness.
Oil based undercoat from Dulux. 
The stuff stinks to the high heavens but it is day and night compared to water based undercoat. I did the same as before standing the timber up touching at one end. No problem after drying, no peeling no issues. The undercoat dried to the touch surprisingly quickly but it took a full day and a bit to dry properly, particularly with the wet weather we are having in Sydney. I guess that a bit of diesel would slow it down a tad, but I did not do it this time. I will try next time I have to use it.   
I also bought another tin of water based gloss Dulux paint since I have lost all confidence in Taubmans. I have to say that from now on, I will never paint treated pine with water based paint unless there is one coat of oil based undercoat on it. I am not sure what it is, if the treatment, the rougher header surface or both, but clearly treated pine and water based paint do not mix.

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## phild01

Sorry to hear that Marc.
I am wondering about the treatment the pine has had on it, how fresh it was, and if a surface solvent was still present.... you can smell and feel this. Treated pine would normally be fine but I thought it was already placed ready to paint, ie and weathered enough that the treatment was shy of the surface.
Personally I don't like Taubmans paints but have found their 3in1 to be good.
I also try not to use oil based primers because it has been my experience that they break down after many years and surface coats bubble the degraded primer away from the timber surface, this never happened when I switched to water based primers. 
Whenever I have had a problem with paint I have rung the technical department up and usually a rep calls around to investigate.  They do what they can to put things right.  Their product advice is this: *New/Bare Work* Surfaces must be clean and dry before painting. Dust down bare wallboards and interior timber. New concrete and cement render must be allowed to cure for 28 days before painting. Weathered timber must be sanded back to a sound surface.  Suitable for exterior applications when used as a primer for timber or on previously painted surfaces. Taubmans 3 in 1 can also be used in "high humidity" areas - bathrooms, laundries, kitchens, etc. under both water based finishes and oil based enamels. 
There is no mention of new treated pine in this statement and I feel you have fair call for redress.  I would contact them and hopefully they will do something to compensate your costs.

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## Marc

No worries Phil, I am not after the money.  Even when my arm still hurts from waiving that old Makita belt sander around. Do you think they would supply a Tai masseuse?  :Smilie: 
I am just glad I was determined enough to re do it. 
You have a point in relation to the fresh treatment on the pine. I didn't think I had to consider this, but it was clearly new stock and it felt a bit like turps on the surface, the rougher header was also very prominent. After the belting I gave it, the timber went flat of course and the oil undercoat that was white, has turned a touch of green, so it seems that the treatments seeped through the oil paint before it dried up.
I thought CCA  treatment was water based copper chromium arsenate, unless they have used a solution of copper naphtalenate, the stuff you buy at the hardware?

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## phild01

The treatments seem all over the place since the scare went out about CCA.  I still much prefer CCA.
I still reckon a call to Taubmans would be worth a go as the labelling should be more helpful.  I once called Wattyl when their Solagard peeled off my gal posts.  They were adamant it should have been fine, called around, saw the problem and supplied me with spray cans of etch primer and a new can of Solargard.

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## eek

Also a big fan of oil undercoat. Never heard of using diesel though! Might give that a go. I love the smell of it and seems to stick to raw timber a lot better than some of the other stuff I've tried, including the Taubmans 3 in 1 and British Paints 4 in 1.  I've used the Taubmans Tradex and Nippon stuff with relatively good luck so far. Too cheap to pay for anything Dulux :P 
As for the peeling - did you test adhesion on other areas that didn't have the wood treatment or weren't touching the wall?

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## Marc

No I did not, however I have a few boards that are not critical still with the original water based undercoat. Will see how they perform.

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## ringtail

I won't be using water based primer any time soon. Glad you did the experiment Marc. Not glad you blew your dollars though. Hopefully you shall remain converted  :Tongue:

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