Cleaning after sanding Pre-Kote and possible filler on WD12

i have applied Pre-Kote to the bottom of my WD12. After sanding do I need to remove all dust and if so what should I us? I’ve got one or two areas that I would like to use some type of filler to smooth out. I was told epoxy would not work but was wondering If bondo would work? I really don’t want to sand all the Pre-Kote and then smooth out with epoxy, that is what was recommended. I’m painting the bottom of my WD12 and varnishing the top side.

Thanks, Neil.

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RE: Cleaning after sanding Pre-Kote and possible filler on WD12

   I recommend blowing the dust off with a pneumatic air hose and then wiping with an acetone-soaked shop wipe. Fair with a compound like Poly-Fair or something similar after sanding at 120 grit or so. 



RE: Cleaning after sanding Pre-Kote and possible filler on WD12

Hi Neil,

I saw your post (and Cody’s response).  So first, I respectfully disagree with Cody’s advice on acetone.   Acetone and epoxy are not friends and you will not like the result of bringing acetone into any kind of elongated contact with epoxy.  It will, in a word, mess it up.  Just see the recent post in the builders forum of what happens when acetone gets rubbed on epoxy:   anyway, fibreglass with polyeser resin (how a traditional glass boat is built) is a different story....but epoxy and acetone are not compatible.

If you have used pre-kote. Most of it has to come off.  It's for filling little imperfections.   its not a base coat or primer compatible for marine use (undewater). When you are done using pre kote, you should pretty much only see glassed wood with little flecs of pre-kote filling in little sratches or dimples or pinholes.  

You should not really be epoxying over pre-kote.  If you have a section  that is not fare and you have painted it with pre-kote, you should just sand the pre-kote off and use and epoxy bondo mixture that you can make yourself with the epoxy you have to fill in/fare the area.

To make your own bondo (that will work in a marine environment), buy some phenolic micro balloons which you can get from CLC.   This is how we make marine ‘bondo’ and it works great and it’s how we fix surfaces that have to be faired and smooth and that we are going to paint over.  It’s one of the core additives I have in boat-building that I use to make smooth hulls  (see the picture I posted of a painted hull night heron at   Before I painted the hull, I squeegied a skim coat of this across the entire hull, sanded it and did not even need pre-kote.  Makes the full look like glass.

Anyway, I hope that helps.   Please be careful about the acetone.



RE: Cleaning after sanding Pre-Kote and possible filler on WD12

   Thanks for the information, not what I wanted to hear. Looks like i’ve Got some more sanding to do!

RE: Cleaning after sanding Pre-Kote and possible filler on WD12


My two-cents worth: Dust is everywhere and it doesn't get along with paint or varnish at all!  You want a dust-free surface no matter what you're going to be coating it with, and a dust-free atmosphere while you're doing it (as much as is possible).  The way I've cleaned up Pre-Koted surfaces (after sanding, sanding, and only want Pre-Kote on small imperfections)  is a thorough vacuuming with a Shop-Vac that has a brush attachment and then at least one wipe down with clean rags liberally dosed with Interlux Brushing Liquid 333.  If possible, wear a respirator and ventilate your shop when doing this (I use a window fan reversed to take air out rather than blow air in).  Your lungs will thank you.  And, if there's too much 333 left on the hull, it may be enough to thin the paint more than is desirable.  So wait for it to dry a bit before breaking out the paintbrushes.  Depending on what kind of varnish you're using on the topsides, follow the manufacturer's instructions.  I've found vacuuming followed by denatured alcohol wipedown seems to work okay.

Hope that helps a bit.  You'll probably get many other good opinions/ideas.  Just as there is more than one way to skin a cat (and who would want to do that, anyway?), there's more than one way to finish a boat...     


Bondo micro balloon mix

I saw someone mentioned using a bondo/micro balloon mix under a painted hull.   I have a number of cosmetic issues that I would like to clean up prior to final white painted hull.  They are not deep but definitely show up.  I am having trouble getting epoxy wood filler or epoxy silica to fill the shallow rough spots.

Bondo would work and sands easily.   Can I put a layer of epoxy over it when finished then continue with painting?   

RE: Cleaning after sanding Pre-Kote and possible filler on WD12

   No, not actual "Bondo" because that's a polyester resin system.  Get a bucket of the phenolic microballoon fairing filler and mix your own up with your epoxy.  CLC has a good price on the stuff if you aren't close to a supply store:  

It worked for me.  Don't make it too thick, but stiff enough that it won't sag. I trimmed the edge of a squeegee spreader so it was very straight and smoothed it with fine sandpaper so it spread smoothly without dragging the mix.  

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