Troubleshooting Adhesion Failure of Lacquer to Caulk
Lacquer may not stick to caulk properly, depending on the products and the technique. September 3, 2010
Question
I completed the build on a large entertainment center. I searched the Knowledge Base and decided to have my finisher use S/W products.
1 - vinyl sealer
2 - CAB acrylic white lacquer flat
3 - medium rubbed clear.
All the joinery was very good, but we decided to caulk some areas such as 3 piece crowns and i/s corners behind glass doors. Everything went great, but after 3 days, the finish has pulled away from any area that was caulked. I have to verify, but I assume he used a standard silicone. He even checked with the rep beforehand to be sure the vinyl blocker was compatible. Any thoughts?
Forum Responses
(Finishing Forum)
From contributor R:
I seem to have problems with caulking under solvent also, so I avoid it as much as possible. If I do have to caulk, I apply the smallest bead I can and allow plenty of time to dry and sometimes use a heat gun to help.
From contributor K:
My gut feeling is that any coating will have problems adhering to a silicone-based product. But new products are coming out all the time, and I've been shown to be wrong before. STAR Finishing Products, now owned by Mohawk, had an aerosol that acted as a blocker between otherwise incompatible materials. See what Mohawk has to say.
From contributor C:
I realize this is after the fact, but I have used the white colored DAP caulk that comes in the small red tubes. In all the years I have used it, it never caused adhesion issues. You do have to remove the excess before it starts to tack up. A cotton cloth and warm water works well.
From contributor M:
We also use DAP caulking to seal the joints in our interior shutters, and have never had compatibility problems with lacquer. Like contributor R, we remove excess and allow time for drying. We spray the paint right on top, no primer in between. I have also had the same results with white lightning caulking. We make sure to get the 20 year rated stuff and stay away from purer silicones.
From the original questioner:
Thanks. I'm pretty sure that the combination of silicone and inadequate curing time caused the failure. The SW rep still says it shouldn't have happened. It was a very fine bead that we used and allowed 24 hours with the temp 70-80 daytime and 50 at night. The shame was that the joinery was good quality and the material was soft maple, so I did everything right except for the decision to caulk. We scraped the joints and touched up by hand. I installed today and the customer paid me for the balance. I got lucky this time. I think the DAP is the way to go also.
