Hello,

So I'm finally getting ready to paint the acrylic lacquer topcoat. I have one more application of high build lacquer primer, a lot of sanding, then just need some warmer temperatures. So my question is should I be using a sealer on top of the primer before I topcoat, and if so what sealer should be used. I'm using TCP Global Restoration Shop primer and paint. I watched a YouTube video of a guy spraying a split window Corvette with Acrylic Lacquer and he used a sealer. However, my google research has turned-up very little that addresses the issue, process, or products.

Thanks
Jack

One of the keys with the whole acrylic system is that it only air dries and can, therefore, be softened again with application of thinner. What this means is that when you spray your top coat over the primer, the thinner softens the top of the primer and creates an extremely strong bond, kind of like welding, between the two.

The lack of such a bond is the reason why 2K clear over base systems often fail - the bond between the clear and the base just isn't strong enough and breaks down with UV exposure. You would have seen the common occurrence of delaminating clear on most modern cars over 10 years old. That kind of failure never happens on an acrylic system - the paint just cracks up if it's old enough and has had too much sun, or it splits from the bottom up if it's been applied too thick.

What you're proposing to do, using a 2K sealer, will stop the topcoat achieving that melted in bond with the primer and you'll be relying on a much weaker bond, plus some mechanical adhesion in two places - the join between primer and sealer and the join between sealer and topcoat. Be a bit like giving the primer a coat of grease, then painting your topcoat over that.

Thanks for the response. During my Google research I read a similar statement regarding the thinner penetrating the primer layer softening it, but that was considered a negative. They indicated that it would inhibit the curing of the top coat layer. Your response makes much more sense that it will enhance adhesion between the two layers. I wrote to TCP Global asking if a sealer was recommended and got a simple answer of "no", with no real explanation. Thank you again for taking the time to provide a meaningful explanation.

Chris, is steering you in the right direction..
Jay D.