I bought a used longboard that had a small patch of delam. I used my dremel to sand into the glass down to the foam, then I removed any glass covering the soft area. I then mixed poly resin with q-cell and filled it. I then sanded it flush. This is where I’m at right now. I have sanded the filler down flush so that it more or less matches the original shape of the board. I know that next is the two patches of cloth and more resin, then more sanding. My question is this: right now the board shape is pretty much back to original shape, everything is flush. When I add cloth and more resin over that, won’t I have a small bit of a buldge on the rail? I can’t sand back down to the original shape because I’ll go right through the cloth and resin back to the filler and what’s the point in that? So should I sand into the filler a bit to make a small impression so that when I add the cloth and resin I can sand back down to flush original shape?
I hope I’m making sense. I’ve watched all kinds of videos and none talk about fixing a ding in this amount of detail.
On LBs with gloss coat, you should sand away some resin surrounding the ding, to create a bit of a low spot. Then, when you do the two layers of glass you should make the first one bigger than the second. This allows you to feather in the repair after you apply sanding resin.
If you have a flexible piece of wood or straight plastic you can hold it on the rail to see if there’s a high or low spot. Or you can eyeball it. So you can sand your filled area a little low (1/16th") and then taper out about 2-3" out into the surrounding area to the outside edge of your work area. Then do your glass patches with smaller on the inside (cut the patch 1-2" larger than the repair). Cut the top layer 2-3" larger. You can lay them both up at the same time. Also I recommend taping off the patch area with masking tape so your patch hangs over on to the taped area just a little (1/2"), then you can cut the edge of the patch along the tape line like a cut lap. Makes the patch neater and easier and sanding easier. Next step is to sand along the patch edge to feather it in to the surface. Then tape off for the fill coat. Pull tape when it’s just gelled, then sand when cured. You will probably need to do a second top/fill/gloss coat, expand out a little. If you tape off, wait until it cuts easy without distrubing the patch. If you tape off don’t press so hard on the knife that you cut into the glass below. I use a small block of wood and 60 grit for sanding the patches and fairing the edges. For the final coat use 100 or 150, then 220.
Hi, I gotta say i disagree with the advice given here I don’t want to say its flat out wrong but I give my opinions on what’s going on in a surfboard and how that applies to fixing dings.
first thing to think about is that the board flexes in use. I don’t care how heavily glassed it is,there is bound to be some flex. Almost all of the flex is carried by the skin, and the core is very weak and mushy, relative to the skin. Even though the skin is very thin, it is carrying most of the loads and variations in its thickness are going to affect the flex in the areas that are thicker than the rest of the board.
second thing to think about is what is usually called hard spots or stress risers. When you replace the soft mushy foam with filler you make a stress riser. When you burry the edge of a piece of fiberglass under more fiberglass, you make a stress riser; the soft, mushy parts are trying to flex but the flexing stops at the edge of a chunk of filler or at the hard edge of a piece of fiberglass so the stress gets concentrated at that edge.
The old school way was to cut around the ding in a “V” shape. Next you would get a piece of scrap foam and shape it to fit the V slot. Glue it in with resin and then shape the foam flush. Then glass . (One old trick was to cut the foam wedge a bit larger and start rubbing the foam patch in the slot. The fiberglass on the edges would actually sand the foam patch down for a perfect fit. Jim Phillips showed me that when I was around 15)
Howzit Mr. Clean. And if you didn’t have a piece foam there was cabosil, oatmeal, coffee,Ha, Ha. I am sure you used whatever in an emergency,I don’t recommend coffee. Now we have Q-sel or ever Aero-sel. Hope things are good for you these days.Aloha, Kokua
Howzit Kokua my old friend. I am old and lazy nowadays. I mix cabosil with lam resin and slop it in the ding hole. Next I take some waxpaper and press it over the ding. The waxpaper conforms to the curve of the rail and the wax makes the repair sandable. Glass as normal.
. Funny story about dings…My friend Craig Bobbit owned Spectrum Surfboards in Florida. They had a big factory and retail shop. (Spectrum is still going strong) Anyway…Craig was the boss and could do whatever he wanted. He decided to do all the ding repars. Sometimes he would fix ten boards a morning session. One day we were shooting the bull and he told me he was making around $600 week under the table and only working three hours a day. Not bad money in the late 80’s.
A few years ago I started a ding repair “how to” that I never got around to finishing. It was intended for an online forum other than this one. Anyway, I found the old pics I made, but the process is incomplete. Just for the hell of it, here’s the pics
No pic for the next step, which is sanding the area to create a slight low spot. But, here’s the pic showing the first layer of cloth after lamination.
Sorry I had to run and didn’t get to finish my post but I do it pretty much the way SammyA showed.
For replacing foam in shallow dings or small gouges I sometimes use two-part urethane foam.
Sanding the glass around the exposed foam I feather it in carefully like a scarph joint.
Technically the smaller pieces of glass should go on top of the larger pieces so that all glass edges get feathered when you do the sanding.
With the glass thicknesses you are typically dealing with on a surfboard trying to do that is just plain silly as the smaller piece will be less than 2 mm smaller than the larger piece.
I just cut both pieces of glass big enough and later on when I fair the edges the top piece ends up a bit smaller than the bottom piece.
When I was doing dings for money, I’d stagger the glass patches so the glass fibers didn’t show as much after sanding. Feathering the layers by sanding too much leaves visible glass strands that don’t look as ‘clean’ when the job is finished.
Any ding that’s too shallow to bother using a foam wedge can be filled with bondo or just a mix of resin and thickener. One of my favorite thickeners is plain old foam dust. I use a Surform to make dust with pieces of scrap foam.
Whoa you guys went above and beyond to answer this, especially Sammy. Even the contradicting repair theories are awesome because I can read the disputed techniques and use any combination that I think will work for me to repair the board. Thank you all so much for this!
Well, like I said…those pics are old. Probably ten years. I happened to find them on a resurrected hard drive just last week. Figured I’d post 'em up. You know the old cliche about a picture vs 1000 words, etc
