# Forum Home Renovation Rendering  Visible mortar lines in render.

## Hortoz

First timer here on your forum....so, hello to all.  
There seems to be stacks of good information on here but, after a search through the relevant sections I'm unable to find anything on mortar lines visible through completed cement render. 
Scenario:
I'm going to cement render a small wall constructed from Verticore/Maxi bricks. The mortar is flush with the face of the bricks.
I plan to seal the wall with a PVC and water mix, allow to dry and then apply one coat of approximately 10mm thick render....job done. 
Question:
I've seen some render finishes with the brick mortar lines visible in the finished wall. 
I've always assumed that this was caused by the mortar 'sucking' or drying that small area directly over the mortar joint quicker than the surrounding section, thereby affecting the curing, resulting in a visible mortar joint.
To mitigate against this, I plan to seal the wall first with the PVC and water mix.............will this work or do I need to go two coats? 
Cheers.

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## Oldsaltoz

The brick pattern showing through new render is normal, it all gos away after fully curing. If is shows in old render water is getting in and it needs a new coat of waterproofing agent. 
You might get a better result by waterproofing the render rather than the wall, it may cause problems with getting the new render to stick. 
Good luck.   :Smilie:

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## mainly-outside

The Brick lines can show up for two reasons; The brick lines or the perps and wells can actually be wiped out with a sponge, this is most common with sponge finished renders and more so again with pre bagged renders. The reason it happens is that the render goes off at a different rate over the perps and wells than what it does over the face of the brick. The brick layers mortar used can vary from brick layer to brick layer due to varying amounts of plasticizer, cement  and different types of blends of sand. To explain how the render does this is by sponging over render on the brick face that is either softer or harder than the render over the perps and wells. Solution - even the rate of suction ( how quick the water gets sucked out of the wet render), there are two main ways one is a scratch coat (two coat system) or sealing the wall with a polymer based solution such as Acrybond.The brick lines will also show up after the wall is finished although they are not wiped out. For lack of a detailed explanation, it is only where the render is drying at different rates which will cause it too dry a different colour. This can be for the same reasons above but can also happen on deep raked bricks. 
If you can relate top the first problem there is no fix as paint will not hide it, and if it was professionally done get your renderer back its a crap job.
If you can relate to the second one it will be fixed by applying a membrane paint ( as is required for all cement render without exception) as this will prevent water ingress and bridge surface cracks created from surface tension as the cement cures. 
Hopw that helps, happy to expand if you like.

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