Once, I saw an auto body repairman spray a contrasting color on his hardened bondo. He sprayed the paint on only after he formed and rough-sanded the bondo. The idea was to continue sanding until all the contrasting paint was gone, leaving only a smooth surface- no pits. Has anyone here used this technique on sanding or finishing coats? Does it work? Does it leave contrasting color too deep, where you can’t sand it out?
Once, I saw an auto body repairman spray a contrasting color on his > hardened bondo. He sprayed the paint on only after he formed and > rough-sanded the bondo. The idea was to continue sanding until all the > contrasting paint was gone, leaving only a smooth surface- no pits.>>> Has anyone here used this technique on sanding or finishing coats? Does it > work? Does it leave contrasting color too deep, where you can’t sand it > out? Noodle. Misting a surface with a contrasting color is an old sanding trick that enables the sander to find the highs and lows. I have used it on the sanding and gloss coats of surfboards and it works. I, however, have found that the use of side lights while sanding accomplishes the same thing and eliminates the risk of paint getting into pinholes. I have not used it on a color coat, but suspect you are correct about the changing depth of color. Patrick
When my brother and I had our boat works we used a similar method to finish sand the sprays on our boat hulls to eliminate the the almost impossible to see orangepeel on mostly bright white gelcoat out in the sun. But, instead of spraying a contrasting color of paint we’d used use sheetmetal dye (I think it came in blue or red) and thin it out and rub it on with rags. It would dry as a light blue or red haze which we would sand out giving us a perfectly fair surface. Excess could be cleaned up with acetone. The blue haze looked so cool that we thought about just clear coating a layer on one of our racing boats and calling it “purple haze”. Alas, we never did get around to it.
When my brother and I had our boat works we used a similar method to > finish sand the sprays on our boat hulls to eliminate the the almost > impossible to see orangepeel on mostly bright white gelcoat out in the > sun. But, instead of spraying a contrasting color of paint we’d used use > sheetmetal dye (I think it came in blue or red) and thin it out and rub it > on with rags. It would dry as a light blue or red haze which we would sand > out giving us a perfectly fair surface. Excess could be cleaned up with > acetone.>>> The blue haze looked so cool that we thought about just clear coating a > layer on one of our racing boats and calling it “purple haze”. > Alas, we never did get around to it. Thanks for the responses guys. As my shop facility is limited, I’ll probably try the technique, maybe in lacquer because it is removable.
I have a general question on sanding that I thought I would add here. I do everthing the old-fashioned way. I make the entire board all by hand - no power tools. I like it until I get to sanding. Sanding sucks. I use a 3M sanding pad (180), then sheets of 220, followed with a dry then wet 400. The finish is simply not as good as “professional” boards. Maybe I just don’t do enough of each grit? Any sanding suggestions? (Other than the obvious of get with it and go buy a good sander.) Thanks, Max
I have a general question on sanding that I thought I would add here. I do > everthing the old-fashioned way. I make the entire board all by hand - no > power tools. I like it until I get to sanding. Sanding sucks. I use a 3M > sanding pad (180), then sheets of 220, followed with a dry then wet 400. > The finish is simply not as good as “professional” boards. Maybe > I just don’t do enough of each grit? Any sanding suggestions? (Other than > the obvious of get with it and go buy a good sander.) Thanks, Max Max, it could be that the sanding pad you are using is on the small side and follows the dips and hills of the resin rather than taking off the tops down to the level of the valleys. i think that i use an 8" diameter pad on my sander and it works pretty well - i get a fairly smooth even finished surface. maybe try starting out with some heavier grit and a bigger pad to take down more of the high spots. also i would say that my hitachi sander is one of the best investments i have made in the way of power tools. it is so much faster. i don’t think i would even build surfboards if i had to sand them all completely by hand. i hate sanding as it is. anyway i hope the bigger sanding block works for you if you think that is what the problem might be. happy sanding. trev
Max: I use a combo of both power and hand sanding and get decent results. I feel that you have to have at least a cheap polisher. Black and Decker was my first and I still use it to buff ,I added a used Makita Variable speed. The industry standard is Milwaukee. I use the power tool with 80 grit to take down the fin plugs/boxes and a once over the laps and entire hotcoat. One more carefully with 120 over the entire board. Next by hand with a 1/2 sheet on a wood/foam block for the flats and all the rails and detail work by hand. Progressive from 120 (problem blems), 220, 400, 600. I too have found out that if you skip or shorten the steps in wetsanding your polished finishes won’t look that good. If you aren’t agressive enough on the very first 80 grit with power tools you’ll never get a fair surface. Recently I switched to a more expensive 3M polishing compoound (liquid) and the extra cost was paid for in less work to get the sanding scratches out. We’ve got some good pros here on Swaylock’s that can give you even more help than I so hang on and maybe they will chime in. TS > I have a general question on sanding that I thought I would add here. I do > everthing the old-fashioned way. I make the entire board all by hand - no > power tools. I like it until I get to sanding. Sanding sucks. I use a 3M > sanding pad (180), then sheets of 220, followed with a dry then wet 400. > The finish is simply not as good as “professional” boards. Maybe > I just don’t do enough of each grit? Any sanding suggestions? (Other than > the obvious of get with it and go buy a good sander.) Thanks, Max
I have a general question on sanding that I thought I would add here. I do > everthing the old-fashioned way. I make the entire board all by hand - no wow, you ARE a brave person. if you build any number of boards, even just for yourself, invest in a planer. it is a MUCH MORE EXACTING tool than your hands and hand tools. and it is much faster. accuracy and consistency is important in board building. you wanna know the REAL secret to a successful sand job? it’s everything that happens BEFORE the sanding. if you have a cr@ppy lam job or hot coat, then the sanding is gonna be a pain. ALWAYS ALWAYS ALWAYS do proper preparation of the current step, to make the next step easier and more efficient. if your lam is good, and your hot coat is just right, the sanding goes fast, easy, and of high quality. i’ve seen sand jobs within 15 minutes, easy. it’s because the surface, to begin with, was smooth, consistent, and light. same thing for the gloss job, if you do one. if you spend a little extra time in preparation, the wet sanding goes really fast. the best way to sand is with (IMHO) a milwaukee - use the still pad first, making a go over the whole board (80). i dont believe in those thick, soft pads - if there IS a lump of resin, the soft pad just conforms to it, rather than taking it down to the rest of the surface. jump to a 150, spending only time enough to remove the roughness and swirls. use a soft pad WITH YOUR HAND only and a 220, cleaning everything up. believe me, it’s easy and works. 5-6 minutes with the first two grits and under 5 minutes for the final.