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  1. #1
    Join Date
    Mar 2005
    Location
    BC, Canada
    Posts
    6

    Question best sandpaper for epoxy?

    Anyone have a favorite sandpaper for sanding epoxy or do they all wear out really fast?

  2. #2
    Join Date
    Mar 2001
    Posts
    400
    If you like hand sanding waterproof paper works well and keeps the dust down, 150 or 240 grit to prep for another coat of epoxy, go up to 600 or 800 before varnish. If you are working with an epoxy that is prone to blush this also saves washing when dry sanding. If your workplace and or wife allow wash with a hose and a cotton cloth until the water sheets off, otherwise wash with a damp rag until clean. When hand sanding always use a backing block, a rubber one works well, but blue insulation foam also does the job. Don’t use wood or anything with hard edges as it will leave scratches and grooves.

    For dry sanding use ALO Lube (Aluminum Oxide Lubricated). This is the grade that the pros use, it will cut faster and longer than the cheep stuff, so will save money in the long run. If you can’t find ALO Lube in your local hardware try an Auto Body Supply, Noah’s also stocks it. Epoxy gets harder as it cures so the best time to sand is as soon as possible, usually overnight depending on temperature and the hardener you use. If you can sand without gumming the paper, do it, it will only get harder the longer you wait.

    My favourite sander is a good quality 6” random orbit such as Porter Cable 7336. Whatever sander you buy be sure it has a ” x 20 stud to mount the pad. This will allow you to use a variety of pads from rigid to very soft as well as adhesive and Velcro back. For plywood construction and other relatively flat surfaces use a firm to medium pad, strip canoe and kayaks with tight curves will sand easier with super soft foam pad. The very soft foam pads tend to sand over the high spots rather than level them so are not great for fairing. Check the Abrasives section of Noah’s website for our pad selection. Start with 80 grit and move up about 100 grit at a time. Grits courser than 80 tend to leave deep scratches, so not good if you are going directly from 2 or 3 coats of epoxy to a paint or clear finish. Don’t try to stretch the sand paper, particularly in the higher grits, when the paper stops cutting it builds bumps on the surface that cut into the epoxy surface and leave circular scratches.

    A sheet finishing sander will also work, but will be slower particularly in the initial 80 grit sand, however I like using this sander for the final fine 320+/- pass before varnish or paint, also between finish coats. Again get a good one, the heaver the better as it will have less tendency to jump around.

    For heavy laminates using 12 oz. or more of knitted or woven fabrics brute force gets it done. Use 40 grit on a 6” sander or for larger projects a low speed 7” buffer/sander with a feathering disk and 40 grit 3m Greencore or similar. This will cut through the surface and take the high spots off quickly, just be careful as this can take off some of the glass as well. Next step is to apply fairing compound, use a drywall knife or a batten, 8” or wider depending on how curved the surface is, the wider the better. When the fairing cures use 40 grit just to break the surface and take off the high spots, but do not try to fair large surfaces with the disk sanders as this will just follow the high spots. The only way to get a fair surface is hand sanding with a board, 3M makes a good 4” x 30” flexible and rigid with handles, or you can make your own out of plywood and sanding belt. Start with 40 grit and just keep pushing at various angles until you start cutting into the glass. If you pigment some acetone and wipe down the surface with a cotton rag before you start board sanding it will highlight the low spots, refill these and board sand again. Use a long flexible batten to check overall fairness and as a final check just go over the surface with your bare hand, you should be able to feel minor imperfections. At this point you can reflect on the money you have saved by not going to a gym for this much sweat. Once the surface is fair you can go back to the 6” sander or a sheet orbital with 80 grit and work up to 220 before applying a sanding primer and paint.

  3. #3
    Join Date
    Jan 2011
    Posts
    1
    I think wet sandpaper is more gud and easy to use..as it prevents the dust and u knw dat wen u r with kids then u got to care abt te kids from dust too...generally this idea works gud for me, i dnt knw how much u guys will agree with me in this regard but wait i prefer i have said it..thanks


 

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