Pre-Kote Primer Problems

Hi All,

I put a single coat of Pre-Kote primer on yesterday afternoon and can't seem to sand it off without causing more problems. The problem probably stems from the fact that I did not thin it when applying it to the hull, so it's probably a thicker coat than desired, but I get about 5 seconds (literally) out of a 120 grit disc before it gums up and doesn't cut anymore.

 I tried cleaning and re-using the discs, 80 grit, 220 grit, a sanding block with all of the above and even sheet rock mesh . . .  all to no avail.

I'm plowing thru, but I fear I'm causing more damage than good (cut thru epoxy in a couple of small places) and it's costing a fortune in discs. At this point I just want the crap off my boat.

Any suggestions?

11 replies:

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RE: Pre-Kote Primer Problems

If you are using ordinary sanding disks they will clog quickly. You can get a little more mileage out of premium disks, but will still use a lot of them. Stick with 120 grit and keep it moving so they don't overheat. And don't put a lot of pressure on. Okay to cut into epoxy but not okay to cut into cloth. -Wes

RE: Pre-Kote Primer Problems

Give it one more day to cure. Drying times listed by manufactures or only a guideline and will vary due to temperature, humidity and thickness of the applied coating. Sounds like you have a thick coat on and that will take extra time to dry. Trying to hurry at this point will just make more of a mess.

RE: Pre-Kote Primer Problems

Thanks Fellas,

Your right, it was a big mess. I put her away til tomorow or monday and see if it cures any better. I will use your advice too, Wes. I was using the premium discs and was still going thru them like nothing, maybe will get more out of them  later.

Thanks again,


RE: Pre-Kote Primer Problems

Something is wrong.  If it's clogging sandpaper, the primer hasn't dried.

There are various reasons why it might not have dried: temperature or surface contamination are the usual culprits. Give it some time, but ultimately it should feel like sanding chalk.  If not, we need to figure out what's wrong.

I've never thinned primer in my life---that's defeating the purpose of primer.  The purpose is to build some depth so that low spots are filled.

RE: Pre-Kote Primer Problems

Sorry I didn't respond earlier, but I lost internet for awhile.

The primer sanded off like chalk today. The can specified 16 hours before sanding, I gave it more than 24 and kept at it for couple of hours and was still having problems. It was plenty hot the last couple of days, too.

Maybe it was the humidity or something. I know the talc in the primer is supposed to absorb moisture. The last couple of days the humidity has been down in the 40-50% range during the day, but getting up into the 70-80% range at night.

Anyway, I got the first coat of Brightsides on her today and she's still looking pretty good. I thinned it, by the way 8)

Thanks for the replies . . .



RE: Pre-Kote Primer Problems

Similar problems here after 21 hours. Location is Bonita Springs Florida on March 19th;  Temperature is in the mid 80's and humidity is low... 34%. I think I put it on too thick. I wanted to get a good build but apparently thats not a good idea. Epoxy is MAS and was cured and sanded well so I now it's not Amine Blush and it doesn't act that way either. It's not bubble gum gummy. It's more that sanpaper clogs and it wont slide on the finish. My hand slides on the paper before the paper will move across the hull. My advice... put it on thin.

RE: Pre-Kote Primer Problems

Finally got the crap off my boat 3 days after application. I had to scrape it off with a paint scraper then sand the resisdue. I went through packs of sandpaper because the stuff clogs up badly. I put the second coat on realy thin this time but it's hard to get a uniform coat when the roller is so dry. I should have thined it. This stuff is miserable to work with. Not sure I would recomend it to anyone. If you use it I recomend thinning and apply lightly. Give it 3 days of dry weather. Sand by hand and use premium no load paper.  Wear a respirator, this stuff will give you a headache and burn your eyes. Very bad stuff to work with.

RE: Pre-Kote Primer Problems

Here's my parting shot on Interlux Pre-kote: I have learned that because of the heavy solids content thick applications will not dry properly. Layers of thin dry coats are the way to go. You don't need to thin it as I suggested in my previous comments. Just keep the roller very dry. After you get a good build, sand with 120 grit premium no-load sand paper. Economy paper clogs up almost imediately. I recomend hand sanding. Sanding with ROS is too agressive and generates too much heat so paper clogs up real fast and leaves globs fused on the hull. If you have major imperfections fix them before you prime. Pre-kote is not a faring compound. It will fill all the small voids and pits however. You should remove most of the primer on the first sanding leaving all your small imperfections filled. Apply a very light second cote. Give it plenty of time to dry, then sand with 220 Grit paper until you have a uniform thin translucent coating for your finish to bond to and provide an even base pigment. White Pre-kote is best for light finishes and grey for dark. You'll go through a lot of sand paper. It helps to vacuum off the paper if you want to get a bit more milage out of it. Whear a dust mask when you sand. Otherwise the powdery dust will iritate your throat and nose. After your done sanding wipe it down with Interlux 333 solvent. I think this is miserable stuff to work with. Interlux should have called it 666 primer instead of Pre-kote. Having said that I have to admit, at the end of the day, you end up with a very smooth substrate for the finish cote.

RE: Pre-Kote Primer Problems

Another graduate of the school of hard knocks. Well done finishing your "education", as well as your boat.

If you want a yacht finish, there's a couple of more things to add to your process. First, use a fairing board instead of a hand-sized sanding block. That will help even out the surface faster.

Second, once the primer is dry enough to sand, use some fast-drying black spray paint to put on a very very light coat of speckles onto the primer. It should just be dots, really, no solid coverage anywhere. Then after you've sanded with the fairing board, you'll end up with areas that are totally empty of primer (high spots), areas that are totally smooth clean primer (sea level) and finally, areas that still have the paint speckles (low spots). Apply your next coat of primer only over the speckles, let dry, add another coat of speckles and sand again. Repeat until either you have a totally smooth, even coat of primer with no speckles or you begin to wonder why the heck are you doing this when you could be out boating.

Again, well done sticking with it and for passing your experiences along so others won't have to suffer.



RE: Pre-Kote Primer Problems

I quite agree with this view
"Give it one more day to cure. Drying times listed by manufactures or only a guideline and will vary due to temperature, humidity and thickness of the applied coating. Sounds like you have a thick coat on and that will take extra time to dry. Trying to hurry at this point will just make more of a mess."

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