I just wanted to talk briefly about the drying process of water-based paint. A lot of people, including decorators, just assume when a coat of paint is “touch-dry”, the drying process has finished. This simply isn’t the case.
Water-based paint dries through the evaporation of water from the material. As the water evaporates from the paint, it dries. However, the water in a lot of paint is locked in place with starch. So, even though it may feel dry, there is still a little bit of water retained in the paint.
That little bit of water makes a big difference, because while it’s there, the paint is still retracting. This means the paint film is still tightening on the substrate. If you apply additional coats of paint before the previous coat has fully dried, the surface tension on the substrate is amplified. This can lead to problems such as crazing or peeling.
You should always stick to recoat times when painting, and just know, it normally takes around a month for paint to fully cure. So, if you’re using a water-based satinwood or gloss, it will be more durable a few weeks after you’ve applied it.
What Other Decorators Think
I asked the question about the drying time of the advance products at a Benjamin Moore product day. It states 16 hrs recoat time on the tin and it’s touch dry within an hour ( under certain climes). The answer I was given was that as soon as it’s touch dry it’s recoatable. Crack on
Air flow way more important than heat. I’d say you can apply a maximum of 3 coats of water-based paint in a day if you speed up the process. First coat is 9am, 2nd coat 12/1pm, 3rd coat last thing. That’s the most I would push it and it depends on which paint your using.
I always follow the instructions on the tin. There’s no point in rushing the re-coat times.
Re-coating too soon just extends the cure time.
I’d say 2 coats of water-based paint is fine, and recoat once touch dry, but if you start building more layers then the ones underneath will take a lot longer to fully cure. Bit like when you go to peel a built up kettle and some layers are still tacky.
The big thing for Water Based paints isn’t heat. It’s air flow. If the room is to hot and the air is to dry you’re gonna have problems with the drying also. I don’t like applying extra coats of paint before my first coat has fully dired. It just causes problems.
If you’re working a 24 hr day maybe you can apply more than one coat in a day…. but over an 8 hr day can’t be a good thing. I can’t see how the paint can cure enough to recoat.
Water based paint needs time to cure, over the set time period stipulated on the tin. It pulls in and hardens, giving a better finish! You shouldn’t try and rush things or your paint can fail.
https://www.owatroldirect.co.uk/product/floetrol/
Floetrol is a useful product to know about when using water based paints especially when painting in difficult conditions.