Lessons Learned Series
Updated: Aug 5, 2019
During one of our recent projects we decided to try some different paint and primer options as well as placing a top protective coat of clear to finish the paint process. The primer we used was Zinsser BIN oil based and the paint was PPG Timeless water based. The final top coat we used was the Rust-Oleum brand of Verathane water based polyurethane.
Once the doors and drawer faces were sanded and prepped for paint we started the priming process. The sprayer we used was the Graco TrueCoat 360 VSP, which is a suction fed handheld sprayer with an airless pump. The primer applied very easily and we really did not have any issues with the BIN primer as it seemed to lay perfectly flat and dry quickly. After two coats of primer we moved onto paint.
When we started the priming phase, the temperatures outside were around 45 to 50 F. However, when we started in on the paint phase was when Winter decided to show up. The temperatures dropped to highs in the single digits and we had to run our shop heaters more than normal to keep it warm enough to spray paint. However, this somewhat restricted air movement in our shop which may have led to the process taking much more time than expected.
Besides overcoming the temperature and air movement issues, the paint process also went smoothy, and after two coats of paint and dry time we moved to the final clear coat. We applied the final clear coat approximately 24 hours after the final coat of paint. The Verathane poly clear applied very easily and looked great right after application. However, after about 30 minutes I noticed some unevenness in the layer of clear and after about an hour I noticed actual cracks in the clear and even in the paint!
I started to figure out that what was happening was that as the clear coat was drying (and it dries quite quickly) it was shrinking and actually pulling the paint as it shrunk. The two layers of paint were separating and creating cracks all over the doors! Clearly I wasn't happy, and knowing that now I would have to spend an entire day sanding down all of the doors and starting the entire process over!
Looking back I determined that the core issues were one, yes, the paint under the clear coat had not fully cured, but also the temperature, lack of humidity, and lack of air flow to help the drying stages. I had used this same paint and clear on a couple past projects in the early Fall time frame and did not have this issue. Another take away is always be sure to read the paint manufacturer's product label. Understand the recommended dry times, application methods, and temperature and humidity based on that application method. This will help ensure that you will not have issues once done painting. That being said, I also try to tell my customers to not use a final coat of clear and instead use a higher quality paint (somewhat more expensive) but also has an enamel, as the enamel will protect the paint. This would be similar to what the clear coat does, and you can also get a higher sheen to provide that glossy look - especially for trim and cabinetry projects.
I did end up spending an entire Saturday sanding down all of the doors and then starting the paint process over. I used an enamel paint that was high gloss sheen and did not apply a clear coat. The outcome was then as expected and the project ended up looking great.
I hope this information will help you as you prepare for your next painting project. I have also listed the paint types I used initially in this project as well as the products I used when I re-painted. Also type of sprayer used as well.
Please comment if you have any further questions or if you have some experiences as well that you could share. Also, thanks for reading and hope this helps!
List of products used and referenced in this blog post:
Verathane Polyurethane Water based
Sherwin Williams ProClassic Enamel