when I go to sand a cured hotcoat, I usually start with 80 and then go to 120, that’s it. The cure hotcoats (pre-sanded) look pretty decent, I ususally just have the rail seam from the tape, the bump from the laps, and a few zits here and there. It seems like when I sand the hotcoat with my sander, it just scratches the beejeezus out of the board, and then it’s almost impossible to get the previous scratches out with the next grit…What am I doing wrong?
Talking hand sanding, start with 50, two pieces, one top, one bottom.
Talking powersander, maybe 120, as our sander did…
Start with 120 on a fesh hotcoat if I’m using a power sander? also, the paper seems to get poweder build-up on it RIGHT AWAY…I have to use probably 8 pieces of sandpaper for each grit!
Wow, I would double check to make sure your sanding resin is good. Maybe not enough or to much surfacing agent or catalyst. What kind of sander are you using? Is it spinning to fast?
We can solve this.
Scott
Maybe ScottW gots it…
Your hotcoat should be fully cured, so only DUST flys around, not gummy grit.
Sounds like you sand too early, while the hot is still soft.
Tap it with your fingernails… I high pitch “tick” should be the result, not a low “thud”…
Yeah, our previous sander, RalphEhni of LocoMotion color fame, started using 120 so PeeWee just followed that idea.
Have your air compressor handy and blow your sandpaper off every once in a while. Are you using UV catalyst? Because if so you will have a more difficult time sanding.
Nope, no UV. I’m using a cheap sander…I usually wait at least 24 hours before I sand the hotcoat.
Tenover - I start with 80 also - really like it as first grit with machine - I suspect you’re sanding too soon, maybe the board needs to cure a little more? or maybe more wax needed in the hotcoat ? That’s my guess - good luck
Maybe because you’re young and strong, you press to hard at to high speed, and dig right into the hotcoat with the paper.
Lower speeds, less pressure, less gummy goo…
Howzit hic, Interesting that you think UV resin is harder to sand. I been using it for about 5years now and never noticed a difference, but then again I don’t use the sun when kicking off hot coats. I waited as long as 2 weeks before sanding a board and I’ve sanded them the day after hot coating and that’s when I notice a difference sanding. Here in Hawaii I find the best time is 2-3 days after hot coating, resin is not rock hard but not soft either, but just right. Aloha,Kokua
Wouldn’t 2-3 Hawaiin cure days equal close to 7 Calif. days?
Our glassing shop was usually 50 nites, 60 mid day.
Kokua-
Interesting, thanks. Maybe I’ll try waiting a few days…
Scott,
I have sanded days after the hot coat and I have sanded that same day. It sounds like your sander is not a variable speed and it is spinning to fast?
Mark
I second the spinning too fast thing. Fast sanding just knocks the grit off the paper. Once the grit edge is gone the paper begins to load up. Paper loads up with those resin rock blobs and starts to scratch the board. Sand paper is the cheapest part of the surf board, use a lot of it and chage it often. When you go semi slow with the sander, you can feel the grit biting into the resin, superfast it just knocks the grit rock off in a few mins, then the swirls start showing up. Buy paper at Harbor Freight 2.99 for 40 sheets for 100 grit.
Any way why are you worried about scratches in the hoat coat? Aren’t you glossing? sand it to 100 grit and put a gloss over it.
-Jay
Quote:
I second the spinning too fast thing. Fast sanding just knocks the grit off the paper. Once the grit edge is gone the paper begins to load up. Paper loads up with those resin rock blobs and starts to scratch the board. Sand paper is the cheapest part of the surf board, use a lot of it and chage it often. When you go semi slow with the sander, you can feel the grit biting into the resin, superfast it just knocks the grit rock off in a few mins, then the swirls start showing up. Buy paper at Harbor Freight 2.99 for 40 sheets for 100 grit.
I think you nailed it right there…My sander IS variable speed, but I bet I’m going to fast. I’ll try slower this time. Thanks.
Yeah tenover, slow that sucker down and let us know what happens.
Scott