I know this is a simple beginner question, but I’ve been searching and I’m getting a lot of threads about epoxy. Also getting a lot of threads re: prepping for hot coat. I’m just wondering what would be the best grit to sand my old poly blank down to. Probably clark foam. It was an old longboard.
I will probably use 6 oz e glass or maybe 6 oz warp. I’ve read 150, 100 , 80 ,60 even 40… I have every grit possible. I’m mostly worried about strength and bonding. I want the best functioning board that looks ok. Not TOO rough, but doesnt have to be very pretty either. Ill probablky add a yellow pigment to the resin as well. I will be using poly resin. For some reason when I see this board finished I see it in a very bright canary yellow. Anyway… Thanks for any help. I know I’ll get varied answers but that’s what i love about sways.
I do mine to 200 grit sandpaper after 150 grit screen. Screens leave a texture you can see if you look close. With tint, you will see the sanding marks. Also finer grit for for less resin absorbtion. Open scratches, more resin.
For bonding strength, did you read the Cerex thread from last month?
No I didn’t but I will be looking for it. I never thought about that. I mean I know less resin=more strength (to a degree) bt didnt htink about tightening up pores in the deck to absobrb less… Thanks. Ill go to 180 220. I have 150, 180 and 220.
I do not get this whole sand em to 220 thing. I have talked to other NEW shapers who do it. I hear a lot about boards delaming and I would think that making the blank that smooth might be a contributing factor.
I do not get this whole sand em to 220 thing. I have talked to other NEW shapers who do it. I hear a lot about boards delaming and I would think that making the blank that smooth might be a contributing factor.
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That is so true. You need some ''tooth'' to the surface, to insure a good mechanical bond.
Bill, is that the same for tint as well as clear? If I tint and stop at 150, I can see dark streaks from the scratches.
Just throwing it out there, but could dust in the scratches encourage delamination? Either way, the only boards I’ve ever had that delaminated were over the foot wells, where the foam underneath was distroyed. With that, the surface wouldn’t have mattered anyway.
Those delaminated boards were polyester resin. I’ve never had an epoxy over PU delaminate. At least not yet. = )
I use 40 for most of the primary shaping using a balsa block and then another balsa block with foam padding. Next up is 80 grit and finally 100 using the same blocks… Screen with eggcrate foam worn 80 and 120. It’s all about how you use the paper and blocks.
I think the super fine sanding came about with airbrushed boards. I hear the foam sanding blocks from Foamez are really good.
A beginner should not get to anal about scratches. Try to keep the stringer flush. Have fun
Its important to have a uniform finished looking shape. The veteran shapers that leave them finished at lower grits, know how not only to adjust pressure, but use papers and screens well worn in. When these abrasives are worn in they may use them for years for only certain applications. Worst is when some ding guy comes in and takes that piece of paper or screen that took so long to get “the feel.” So that old piece of 100 grit make actually be closer to 320 that what it started at. Those burnished screens conform to the rails, and contours, and finish with less loading, and tearing of foam. Symmetry, and balance, are the goals.
A rougher finished board may not look as nice, but has a better surface to mechanically bond as Ace, and BillT emphasized, but a finer sanded board will drink less resin, be easier to paint, and laminate; this should be considered also.
Was waiting for comments along the lines of the Rat. It's all in what the final finish will be. Leave scratches and a paint job or tint will look $#!tty. Yes I finish with worn out screen and they finish slick. The way I like 'em. What grits? If I didn't know how to use a Skil; Yeah I'd probably have to start with 40 or even 36. But since I get my initial planing done with the Skil to a fairly clean finish I usually knock down a few tails with the Sureform and go straight to 80, 100 or 120. Then to 150 or 180 screen and go over the whole thing with a piece of worn out 220 screen that I have had for a long time. Nice and slick. Will paint or tint well. I have never had any delam problems..
I am not saying to leave a bunch of scratches tears and pits. I am saying that with proper technique, soft pressure, AIR and end to end direction all you need is 100 ok 120grit sand paper. I like my paper best after about 5 boards or so. I have been using the same screen for a long time it is soft and flexible. I usually use em till they start to fall apart. I did LOTS of tints Ice blue, root beer, deep reds and the always fun smoke grey. These need a sharp blade in the hand plane and careful sanding or you see EVERYTHING, not good. I do have some “special pads” for stubborn blanks. Again it is all about technique, I learned from some pretty good ones and this is how I was taught. Use whatever you want it is just sandpaper. I guess I will go back to making ‘’ $#!tty’’ looking surfboards.
I really appreciate all the feedback. Thank you. But i must disagree with keeping an 80 grit sheet until it turns ito 200. Thats retatrded. Sand papers 39 cents a sheet. Buy some new fresh predictable 200 and use that. Worn 80 is not 200. Its 120 here, 180 there, 93 there and 240 in the corner. I know you guys are super good at what you do and have sanded thousands of boards, but ive been through thousands of sheets of sandpaper too. Just not extremely experienced in sanding foam. And keeping old sandpaper has never proven as effective as a new crisp sheet of the proper grit. Thats false economy and weird false kinda romanticism. I think ill take it to 120 or so and leave some teeth for it to bite into. I can get it super smooth with 120. It will look great AND be strong.
P.s. i dont wanna sound unappreciative or make it like you guys arent great at what you do, but I dont want new guys seeing this and thinking its ok to hold on to a piece of sandpaper for years. Its more trouble than its worth IMHO. I know someones gonna flame me, but I have to speak up.
Well it sounds like you think you know what your talking about, and you say it with certainty. I must admit you made me laugh. I know Ace knows what he’s doing, don’t disagree at all. As for the flaming part; that’s not my job. I agree with you on the holding on to a piece of sandpaper for years to; I just leave it in the shaping room, when I am finished, and most of the time its there when I return. I am not attached to sandpaper that way; although I could be if I didn’t clean the nozzle of my can of 77 from the boogers.
Great think about fresh sandpaper is its abrasive, yet its just not worked in correctly, like you.
GR, you sure are funny too, worked in correctly, haha
Could you explain from your experience what the difference is between worn in paper and fresh, say, 320? Does it just not draw as good? Cut as good? It is all about the feel innit?
Good one GR. I know im abrasive. I cant help it. I do try to not offend tho sometimes. Sometimes i miss. Sways is full of more useful info than anywhere else. And i do respect everyones craft. Immensely. I believe handshapes boards have soul. But i dont believe the sandpaper superstition and i feel like its detrimental to your finish. Maybe i should have phrased it this way originally.
Ive worked with wood a little bit, but most of my experience with sandpaper was 400 grit and above. You really dont wantto work your way to 1200 grit then pick up an old 1500 or 2000 and put a big ole scratch in someones 54 chevy pickup. Or a 99 hyundai for that matter.
That was a weak apology for my abrasiveness above. Heres a better one. I apologize. I sknt mean to be abrasive or disrespectful to anyone. Especially the guys on sways trying to help. S
Thing is as much as the gr dishes it out he can take it too, and for me its all in fun and jest; nevertheless, some guys around here are wound up so tight, I could see them having a stroke or a heart attack, instead a good light hearted laugh. Ace is a great shaper, and I seen many of his boards riding the afternoon winter glass, with a brilliant sun setting the whole place ablaze.
Use it often, throw it away, get a new sheet...use that a bit, den throw it away too. Go through a whole brick ofsand paper in a few days if possible. Maybe a sheet gets a speck of gunk on it...throw it away and get a fresh one.