Wet sand Pre-Kote

In tips it states "Sanding hi-build primer sends up huge billowing clouds of white dust, so it's best to do it outside on a windy day." Can I wet sand? It's 26 degrees out and our warm days are the high thirties so I can't go outside. How much odor from primer? I do have a  power vent to outside which helps but not 100%. I am not worried about me I wear a mask,  I'm thinking of my spouse :>). How does it compare to Varnish?



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RE: Wet sand Pre-Kote


 I just launched my Dory and I sanded the Pre-Kote primer three times inside and without the cloud. Used Norton 220 grit paper on my Bosch orbital sander, mayber turned the speed down to about 3 (6 is highest) and used my old ShopVac with the Bosch adapter and a piece of electrical tape once around the vacum hose to make the adapter fit tight (in place of the nice filter Bosch provides). In the ShopVac, I had installed one of those paper filter-bags that they say to use for drywall dust. No noticeable dust, let alone "billowing clouds" the book predicted.

Good luck.


RE: Wet sand Pre-Kote

If hand-sanding, yes, wet sanding is fine. Better in my opinion. No cloud and a smoother finish). It's how I always do it.

But you'll need to let it dry between coats and, although you can use water to wash most of the wet dust goop off (I hosed mine down, but that was in summer!), you'll still need a tack-cloth or similar to remove the residual dust before applying the next coat.

If machine sanding, I definitelty agree with JB above. A good filter on a good sander will produce very little dust (but a poor quality set up is next to useless). I'm sure you know this, but for in case anyone reading this doesn't, NEVER wet-sand with a power sander...! Bzzzzzztt :)

 Re the odor of pre-kote, it's not too bad, and I didn't have any obvious reaction to its fumes. But, that isn't necessarily a reliable guide to how eg toxic it might in fact be.  I'd let it get touch-dry (so no dust etc sticks to it) then open windows for a while to vent the fumes...


RE: Wet sand Pre-Kote

A word of warning, do not wet sand Pre Kote. Is will absorb water once the skin is broken. Wet sanding is the preferred method between coats of brightsides or varnish, but not Pre Kote. Hand sanding with a fairing board will give you a near perfect finish without the billowing clouds of dust a sander will create. 

 Here is my recipe for a finish that many will swear has been sprayed. The surface must be sanded smooth with a final finish with 220 grit paper. There should be no glossy spots in the epoxy which indicates a low spot. Minor scratches and pin holes will be filled with Pre Kote. Roll and tip 2 coats of Pre Kote, allowing proper time between, for it to dry. This is where a fairing board or at least a sanding block will make ot break the final finish. Resist the urge to "get it done" at this point and leave the ROS on the bench. Starting with 220, sand the surface with long ever strokes. Resist the temptation to concentrate on individual flaws in the surface, you will only create depressions that will show up once the glossy stuff is applied. Once you are satisfied with your work, go over it once more with 320 grit. The finer scratches of 320 are far less visible in a newly applied coat of Brightsides. Wipe every inch of the surface with mineral spirits and follow it with a tack cloth to remove all of the dust.

 Now for the good part, my mix for brightsides is the same as varnish. I Mix 10% mineral spirits and 10% Penetrol to my paint. The mineral sprirts slow the evaporation of the solvents a bit, and Penetrol is a flow agent. Together, they are magic in marine polyurethene. Roll very thin coats on and tip with a foam brush. Between coats wet sand with 400 grit and wash the surface with clean water. Do this 3-4 times and you will have a finish that rivals a new car.  

RE: Wet sand Pre-Kote

"A word of warning, do not wet sand Pre Kote."

I defer to the experts, obviously, but I've never had a problem with wet-sanding pre-cote. Then again I live in Australia. A big, dry, desert (except when we flood!)  where nothing stays wet for more than a few minutes...

Given its powdery consistency, I wouldn't be surprised if it's not stable over hours, as opposed to minutes.



RE: Wet sand Pre-Kote

Thanks everyone for your responses. Joey I will follow your advice. I figure two more weeks I will be ready to hit the water, now I have to hope the ice moves out by then.


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