Sanding epoxy - how much is enough?

I can't say that CLC didn't warn me, but I've been sanding so long I'm losing the will to live.  I've built a Tenderly and have completed coating the entire craft with several coats of epoxy.  In preparation for varnishing the interior, it's getting it's last sanding, which, because of the curves, seems to have to be mostly by hand.  My question is, how much is enough?  the manual says to get everything looking cloudy with 220.  But what about the rough areas around fillets, under seat supports, under floorboards.  Will varnish adhere to the odd small gloss section of epoxy that resist sandpaper in divits?


6 replies:

« Previous Post       List of Posts       Next Post »

RE: Sanding epoxy - how much is enough?

   Ha!  Well, you are still writing coherent sentences so you haven't gone too far.  :-)

The answer is different for everyone, i'm sure.  I have a bunch of the abrasive sanding sponges that are about worn out, so I wrap a 1/4 sheet of my preferred sandpaper around it and can flex it enough to conform to most corners and curves to sand those spots that wear out your fingers when you are just using a piece of sandpaper in your hand.  And yeah, some of the spots where it's a local low spot, I'll just rough it up without trying to sand down to that level, mostly because I'd have to remove too much material around it.  The kit epoxy is a nonblushing formula, so it's not really a matter of getting the finish to stick to the surface, more to get the surface smooth so the little bumps and craters don't show through.

Also, I saved the 220 grit for the very end, using 120 or 150 for most of it, but then, I went for mostly painted finish.  The varnish will stick just fine, so long as you clean all the dust off.  BTW, very thin coats of varnish, especially inside, because it will want to run and sag otherwise, especially after you turn your back and stop looking at it.  Ditto for the polyurethane paints (Brightsides).

RE: Sanding epoxy - how much is enough?

There is a product called Curve Flex Pro which comes in many sized and shapes.  It is bendable and will take the shape of the curve.  I use 2 3/4 long board sandpaper which is PSA and comes in several grit sizes.  I purchase these parducts on Ebay and they are not expensive.  As far as how much sanding is necessary I use the 10 foot rule.  If it looks good from 10 feet away then it is good.      

RE: Sanding epoxy - how much is enough?

Green Scotch-Brite does a good job of scuffing the surface before paint/varnish. It's also the kind of material you can wad up, stuff into small corners, and twist.

RE: Sanding epoxy - how much is enough?

I'm a big fan of ScotchBrite abrasives too, and they're not all made by 3M either. The biggest advantages are they're available most everywhere, they're not expensive, they follow contours very well, they last a long time and can be used either dry or wet. One of my favorites for knocking the gloss of hard epoxy off is this maroon stuff sold under the Norton Abrasives brand at many hardware stores as well as on-line.  Sandpaper's has its place of course but for the tightish & curvey shapes inside boats there are alternatives that work their magic with less fuss.

RE: Sanding epoxy - how much is enough?

Bronze pot scrubber might work, too.  Just a stray thought from someone only halfway through his first cup of morning coffee, not the voice of experience.  <;-)


RE: Sanding epoxy - how much is enough?

   Nothing to add on the sanding that hasn't already been said, but it is critical that you not only clean the surface well after sanding with vaccuum, dentaured alcohol, etc. but that you allow whatever you use as a cleaning agent to dry. I was over enthused and wound up having some still wet tiny pockets in the epoxy that when varnished over slowly created the grossest milky yellow spots in the varnish. I had to sand the ENTIRE Northeaster Dory down to the epoxy again to fix it. I wanted to kill myself at that point. Ultimately it came out fine, but I added some hours to the build due to my own impatience and stupidity. Probably not uncommon. 

« Previous Post     List of Posts     Next Post »

Please login or register to post a reply.