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arg, i cant figure out how much to thin the paint! Im getting tons of bubbles and runs! I think its too thin, after 3 coats it isnt even coming close to covering up the primer exct. It just looks like its been tinted



As noted in the past... each layer does look like just a tinting. It is the culmative effect that gives you the final result. Layer upon layer upon layer of 'tint' eventually adds up to a solid color.

So don't get worried about how thin it is applying and not giving instant coverage. You job as you build the layers is to get them as smooth as possible and minimize the bubbles.

Bubbles are 'somewhat' normal during the course of applying the paint. By using the high density foam roller you will minimize the bubbles transferred from the roller to the painted surface.

By using a cheaper foamy type roller... you are almost guaranteed of bubbles when you lay your coats on.

That is why we went in to a fair number of discussions during the course of the thread about how to work the surface as you lay a coat of paint on. In some cases it is a method called 'tipping' where you gently glide a paint brush over the bubbly surface to pup the bubbles.

In some cases you use two high density foam rollers.... one for painting... and a clean one for doing a quick second roll over the surface to pup the bubbles.

In some cases you can get away with gently blowing on the bubbles and they magically disappear.

In some cases you just have to stand back and do nothing... the bubbles will pop on their own. If they are not popping on their own, it usually means that you need to add some more thinner.

Just think of it this way... the only reason a 'bubble' can survive is if its surface tension is sufficient to hold it together. If it can reach the point where the bubble has dried and still held its bubble shape, then this means there was too much paint in the mix - and the surface of the bubble was able to dry and harden without breaking. So by thinning the paint mix more... the thinner will weaken the surface tension of the bubble and allow it to 'pop' on its own long before the paint begins to cure or harden.

Runs are simply natures way of telling you to not overload the roller with too much of your thinned paint mixture. The best time to tackle them is when you first spot them - and hopefully the paint hasn't begun drying yet. Simply take your roller to it and hopefully you can work it out by spreading it around. If it has dried when you spot it... well it is best to sand it out prior to the next layer of paint being applied. If you don't remedy it and instead just keep adding layers of paint... it will basically amplify its appearance. So nail it early rather than later.

The other thing that might cause bubbles or 'pits' is when the surface was not fully cleaned prior to the next application of paint. Again, this has to do with 'surface tension'. The picture you provided almost looks more like 'pits' where the subsurface ( the one being painted over ) had particles of some foreign matter on it. In a situation like that the overall tension of the paint surface will be 'repelled' from the spot where the contaminant is. In that case you just have to make sure that you go through the ritual of wiping the surface down with a tack cloth and then a quick wipe of just thinner ( only on a dried surface ) to ensure that there is nothing on the surface being painted that could cause a spot to repel the paint and cause the 'pit'.

Hope those ramblings help you out...

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Last edited by Marq; 05/13/07 10:10 PM.