I just finished sanding the first coat of Pre-Kote applied over a full-hull fibreglass on the Dory. I was surprised at how little the Pre-Kote flowed and how quickly it dried; a lot of tracks of roller and tipper brush remained. I was surprised, too, how tough the Pre-Kote is after drying, and how long it takes to sand out tool tracks. This is to me a bad combination.
In applying the second coat of Per-Kote, is there any experience out there with adding a bit of Interlux Brushing Liquid 333 to Pre-Kote to kill the clumping tendence and orange-peel effect of the short-nap rollers?
Laslo, any advice to interject?
Interlux Pre-Kote doesn't "flow." It's meant to be a thick coating that gets sanded, filling the low spots in the surface while the high spots are sanded away. I use primer as a fairing compound, essentially, not as a paint coating. The high-build qualities of the primer don't lend themselves to flowing out smoothly, or really behaving much like paint at all. (The active ingredient is titanium dioxide: talcum powder.)
I never, ever use a brush with that primer. Since brush strokes won't flow out, they become instead deep "valleys" in the finish that will themselves need filling. Instead, I use a roller alone to apply primer. This leaves a somewhat mottled surface, but the roller is great at getting the primer on in a coating that is a uniform thickness.
Denny,
The recent Pre-Kote thread has some good info in it.
My experience is with System 3 Yacht Primer (which I wish CLC would stock), not Pre-Kote. Since both are high-build primers there's some similarity, but someone with Pre-Kote experience should jump in here to give you the real info.
The toughness, BTW, is a good thing. You want a tough layer to support your paint. One thing I can suggest is not to sand the first coat. Put on 2 or 3 thin coats before sanding. That way you'll get a good buildup and fill in some of the previous coats' tool marks. A thicker set of coats also lets you use a more aggressive sandpaper which makes the initial smoothing easier.
As far as thinning, that's a question for the Pre-Kote users.
Good luck,
Laszlo
I just got done using the prekote. I really like it. I thinned the first coat 10%. I applied with a 6" white foam roller and no tipping. The key is to apply rather thin. It took about 26 hours to dry fully at about 50-60 degrees in my shop. When fully cured it sands really easily in big clouds of dust. I sanded with 220 on a random orbit sander.
The second primer coat I did not thin at all and it came out great and filled the little pinholes I had. I hand sanded the second coat with 220 after 24 hours and have now applied 2 coats of brightsides. I gave each coat 24 hours to cure then wet sand with 320 before applying another coat. Again, thin coats are key and I do tip the brightsides with a brush. The results are great. I will apply the last coat today. So far this has yielded excellent results.
If youre having trouble sanding the prekote, I have to think it hasnt fully cured.
So. Do we thin the first coat 10% or not. And if so, with what? Any opinions?
Although I did thin the pre-kote I do not think it makes a noticable difference.
It was however noticeable with the brightsides. The lap marks and tip brush strokes seemed to dissapear better when thinned 10%
In general, I don’t think you want to be thinning a high build primer. Kinda defeats the purpose of the product.
FWIW, the only time I've ever seen a manufacturer recommend thinning a high-build primer was for spray application in a hot and dry environment. Even then, they recommended that a test coat be applied unthinned first to see if thinning was truly necessary. It was not an Interlux product.
Laszlo