Surfing School - Repairing - Delaminations
Delaminations are basically an air bubble or soft spot that appears under the board's surface. They are usually caused by a small hold in the outer glass that allows water to seep into the blank underneath. Unfortunately, the longer a delamination is left unrepaired, the worse the condition will get. A chip or crack in the board's nose or tail can also cause cloth delamination.
Repairing a delamination will nearly always result in a discolored and often ugly spot on the boards surface. If the delamination is still very small, a quick fix that sometimes works is to use a syringe with laminating resin mixed to cure slowly, A large needle is necessary to insert the resin into the delaminated area. Put a very small air hole into the middle of the delaminated area first, then try to force resin into the edges of the delaminated area with the needle. The last area to fill is the middle air hole.
If the delaminated area has grown too large for a needle (over an inch or so), the best way to fix the problem is a little more involved. First, lightly sand the delaminated area plus a small overlap. Use a razor blade and carefully cut the cloth around, but just inside, the delaminated area. This might be difficult as the cloth is hard, so use the point of the blade and jab slowly as you work around. Coat the delaminated area and the bottom of the cut out cloth with finish resin, then insert the piece back into the hole. When the resin starts to cure, but before it gets hard, tape the entire sanded area off and hot coat with finish resin. Sand and buff to finish.
When the delamination is over 5 or 6 inches across, it's best left to a professional to fix. An inexperienced person can greatly damage a board if the following process (probably one of several) is not followed correctly. Here is how we fix this type of a problem.
Using the sandpaper edge on a disk sander, carefully sand the glass around the edge of the delaminated area until you are close to but not quite through. You don't need to sand completely through as anything thin enough to easily cut with a razor (or a Stanley knife blade) is acceptable. Once the delaminated cloth has been removed, use a razor to trim any edges of the delaminated cloth that still extend over the foam. There should be very few places if the sanding and removal was done carefully. Save the removed cloth if the board has pigmented color, or if it will be difficult to match the color on the board.
The big problem with delaminations is that there will be a dip in the foam under the delaminated area when the cloth is removed. There may also be some discoloration. Here is where experience is a must. If there is discoloration, we sometimes slightly sand the foam to expose a whiter surface. The problem is that this causes an even larger dip that must be filled in. Unless you know what you are doing, don't sand.
Tape around the delaminated area, about 1/4 inch or less from the cloth break just outside the entire area, and rough up the exposed surface with sandpaper. There should be no edges sticking up. Next, cut a piece of 4 oz. cloth just larger than the cut area. If you are going to re-install the removed glass, slightly sand (rough up) the surface area of the cloth prior to using so the resin will stick. Don't do anything to the bottom of the cloth (the foam coated side). Resin (non-finish resin) under the removed piece and replace it, then lay the 4 oz. cloth over the entire area.
Using a tongue depressor, saturate the cloth (with the same non-finish resin) to the edge of the cut area. This should be a thick saturation, not a thin saturation. If done correctly, there will be a slight overlap of the resin on the good surface area, but only slight. Use the depressor on edge to smooth the resin down.
When the resin starts to set, remove all non-saturated cloth and any cloth sticking up around the edge of the repaired area. Using a 2 inch brush, apply a thin coat of sanding resin over the entire exposed area, and remove the tape once this starts to set.
We use a vibration sander with fine grit sandpaper to smooth the surface prior to glossing. After sanding, re-tape, apply a fine coat of finish resin, and remove the tape when the resin is close to setting.
If the removed cloth is too damaged to replace, you will need to build up the area under the delaminated area with a layer of cloth (sometimes two layers). We generally cut a piece of 6 oz. cloth just smaller than the removed area, and squeegee it to the foam with non-finish resin. If this doesn't bring the level up enough, apply a second layer of cloth, but if you do, let it harden before applying the outer 4 oz. layer. Also, make sure you used bleached cloth. All other steps should be the same.
We personally think pigmented resin looks best for this type of repair. If you are not replacing the removed piece, only pigment the outer 4 oz. layer. If you are replacing, pigment isn't necessary.