Retarding Waterborne Lacquers
What's the right additive to thin the formula and slow down the dry time? February 2, 2011
Question
I am spraying SW Kem Aqua WB primer and pigmented lacquer. I'm in southern California, with low humidity and high temps. Gravity feed cup gun. I'm getting dry patches in the finish. I have tried increasing my finish volume and amount of overlap to the point where I have had to remove a couple of sags and re-spray. I need to slow down the dry speed. I called the SW rep and he said to thin with water. I've read that water may not be the best retarder because it has a higher surface tension. How can I resolve this problem? How can I remove one of these overspray spots on an installed cabinet?
Forum Responses
(Finishing Forum)
From contributor M:
When spraying Sherwin Williams Proclassic latex enamels, I thin with water, but find adding Floetrol additive, 2 oz per quart of paint, slows my dry time to a more workable rate. I do not know if it will work with the products you're using, but it might be worth trying on a sample piece. I adjust the amount of water for thinning by the amount of Floetrol I add, to keep the paint from getting too thin. The Floetrol is pretty thick so it does not work as a thinner only. In other words I have to use some water.
From contributor B:
You need to mix 1:1 water and butyl carbitol, then add at about 1 ounce per gallon. This should resolve your issue. If butyl carbitol is not available (check with Shirley Williams) then use butyl cellosolve, but make it 2:1 water and BC.
From the original questioner:
Thanks, but Floetrol is a latex paint additive and Kem Aqua is not latex, so I would be afraid to add it. I love Pro Classic but don't use it on cabinets unless I'm brushing. Actually, I don't think PC is latex.
From contributor G:
Glycol ether DM, in small amounts, will retard waterbornes. Have you tried a larger tip on your gun to get more product on the work? How about a narrower fan?
From contributor W:
You said you were spraying with WB Kem Aqua primer and pigmented lac. Aren't those waterborne products?
From the original questioner:
Yes, Kem Aqua primer and pigmented lacquer are both waterborne products. I usually have really good luck with them. Wonder why more people don't use them? I am using a larger tip than recommended. Whenever I try to put more product on the cabinets by increasing tip size, increasing the amount of overlap, decreasing my air, etc., I get sags. I need to stick with a thinner coat that dries a little slower. They recommend butyl cellosolve but I have not been able to find it in a paint store. The SW industrial coatings facility is close enough to go pick up finish, but too long a drive just to get a gallon of retarder. Just read on this forum that water was not the best choice. Think I'm just going to finish spraying and wet sand.
From Paul Snyder, forum technical advisor:
I've used the Kem Aqua a number of times and had good results thinning with water 15%. It worked best when I sprayed a full wet coat at 3-4 wet mils.
From contributor J:
Contributor G hit the nail here - look for a glycol type retarder that is made specifically for water base finishes. If Sherwin Williams does not sell it, others do.
