I wonder about a couple of things regarding paints for home use (such as painting walls): * Why is latex paint so popular? * Since when has it been so popular? * What was used mainly before latex paint? * What about epoxy paint? The only one I found was intended for garage floors?

Why is latex paint so popular?

Because it's pretty good, now. Easy to use and more durable than in the past. A lot of work has gone into latex paint because of the toxicity of other types.

The low volatile organic compound emissions of latex and acrylic-latex compared to alkyd/oil paints make it easier to deal with when painting the interiors of an occupied space (or soon-to-be occupied space). The higher water vapor permeability makes it somewhat less susceptible to blistering and peeling too, since seasonal moisture cycling can occur at lower vapor pressure deltas. (This is particularly noticeable on wooden exterior siding that is painted only on the exterior- alkyd paints will separate from the wood after a few seasons/years of uneven drying, whereas latex hangs in there.)

Epoxy paints are usually highly vapor-retardent so be careful to avoid building unintended moisture traps in the assemblies where you use them.

OK thanks for the input. I looked up the perms for epoxies is around 1-2 US perms compared to 5-10 for latex paints. To my knowledge, in Europe, almost no one uses latex. They try to market it as "luxury finish" but I don't think it will catch a market share, unless it's a different latex from the ones sold in the US. The epoxy based paints are used everywhere interior and exterior but as far as I know not on wood. Generally construction in Europe is a thermo block type and stucco interior and exterior. The perm rating of the wall is hence around 10, then it's painted on both sides with a 1-2 perm paint. Unless there are water leak issues I wouldn't say it's a problem with moisture being trapped. The main issue I have here with latex paints and I have tried a lot of different brands, is they are extremely expensive and don't cover well / at all. For example Behr at HD is pure water. I don't believe people actually buy this a second time! In Europe the last time I had to paint two coats was in the 80s. Generally one coats covers everything, except graffiti of course. It feels to me they water down the latex paint so they can sell more of it. Painters probably welcome it because they can justify 2x labor..... For the DIY homeowner it's frustrating to have to spend so much money on paint and then so much time to paint everything twice, especially when the entire house is being renovated. What I like about latex paint however is you can wash it. The epoxy paints tend to have a rougher surface which keeps the dirt in. I understand the advantages of latex paint especially since we are dealing with thermally expanding materials in the US but its density and cost is what bothers me. Can we mix our own paint / or somehow mix something into the paints to make them better?

OK one mistake here I made,



the main ingredients in European paints are not always epoxides, it's:


polyvinyl acetate emulsion (PVA)


and

titanium dioxide, which is also used here I believe it's the 'white' in the paint, isn't it?

So where can we buy paints based on PVA? Does anyone know a brand name?

If you uses 1-perm paint on the exterior of wooden siding that hasn't been similarly painted on it's back side, in colder US climates you can expect it to blister and fail within 5 years on sides that get driect sun, and in some cases it can cause the wood to cup & split. It's more about the dimensional changes of wood with moisture drying at different rates on each side of the material than thermal expansion, and the vapor drive when the sun heats up the moisture in the wood breaking the bond between paint & wood. With higher-perm latex you still would want to paint the back side, but it'll still dry reasonably quickly in warmer weather and won't have as much bonding issue.

Lower perm paint can (of course) work fine on aerated autoclaved concrete blocks or similar with stucco or plaster finishes though, since the moisture content doesn't affect the dimensions of the material. Less water wicks into the concrete from the exterior through epoxy than you'd get with dew-wetted latex on wood too.

this is intersting Dana. I had some cement block painted inside and outside with latex primer + paint (I just learned there is no latex in latex paint, hence the confusion!)
and it blistered outside in a handful of areas. Since it's a 90y old house, I suspect there's plenty of oil paint underneath. We had scraped it last year wherever it was blistering, and it was a lot! the new paint sticked well except a couple of spots this year came off. job was done on a dry day of course, i planned to have the wall as dry as possible before starting work.

now at the interior the wall was painted the wrong color. I gave them a new bucket and said "back to work"
however, now the wall looks terrible (also cement block but the interior side, no stucco) the paint cracked everywhere. it looks like a map of some wet land ;-)

did this happen because they didn't wait long enough before applying the second coat?
See that's one of the things I never seen happening with european paint. something must be different in the mix! also the paint here creates a like skin that comes off if you use the roller over it before it fully dries. again, never seen before...extremely weird for me!

When I bought epoxy based "garage floor" paint, this didn't happen. AND I immediately recognized the smell, that's the stuff we use back home!
but I am still puzzled what the difference is?

Posted By Sav on 11 Jun 2012 05:13 PM
OK one mistake here I made,



the main ingredients in European paints are not always epoxides, it's:


polyvinyl acetate emulsion (PVA)


and

titanium dioxide, which is also used here I believe it's the 'white' in the paint, isn't it?

So where can we buy paints based on PVA? Does anyone know a brand name?

Home Depot

THis isn't going to help your theory of the differences between American and European paint much, but Polyvinyl Acetate (PVA) IS the "latex" in latex paint.

you are right, i start seeing it on the labels. there IS a difference but I can't tell what it is. the fact that the paint creates a 'skin' is just weird.

perhaps I sniffed it for too long and don't remember exactly how it used to be ? (^_^)

just to be clear, I am not saying the US paint is inferior. it has different characteristics that require a different painting skill -> hence it's frustrating to re-learn. somehow my gut feeling is the paint is made here this way because here we use drywall and there we have stucco, obviously different requirements that can't be satisfied by the same paint ingredients. OK PVA is not the difference, granted!