Will sanding resin stick to sanding resin?

I routered out for a single fin Bahne box, and then resined the box in without using foam filler in the resin. Now it is perfectly (and painfully) obvious that I did a hack, amateur job. But, the resin, solidified, is still about an eighth of an inch below the level of the bottom of the board (if that makes any sense), so I have to add a little more resin to bring it flush. My question is, 1. at this point will sanding resin stick to the previous layer of sanding resin? If so, 2. will adding foam filler work at this point? Finally, do I mix in the foam filler before or after I mix in the catalyst? This is my last thing, as the board is already sanded and waiting for a hollow, offshore day. Oh, maybe I do have another question. How big should my fin be on a retro seven foot single fin?

My question is, 1. at this point will > sanding resin stick to the previous layer of sanding resin? Not unless you sand it or romoves the wax in some other way. I would try to wash the wax off with acetone then rub up the surface with a little sandpaper, then wash again with acetone just to be sure.>>>If so, 2. will > adding foam filler work at this point? Finally, do I mix in the foam > filler before or after I mix in the catalyst? I would add the filler after mixing the catalyst. Getting the catalyst well mixed into the resin after you have added filler is gonna be hard. regards, Håvard

I would add the filler after mixing the catalyst. Getting the catalyst > well mixed into the resin after you have added filler is gonna be hard.>>> regards,>>> Håvard Havard, I add the filler first, then the catalyst, even if it is chopped fabric or Q-cell. I feel I get my consistancy correct thata way. My 2 cents, Colin P.s. when are ve getting a spell chex on dis site?

We’ve got one…Her name is Coral!

As far as your fin box goes, I would use laminating resin. Once you add your pigment to it and milled fiberglass (or cabosil or whatever) and it kicks, it will sand out with no problems. As long as it kicks off good it will not gum up on you. If you don’t have any laminating resin the hotcoat or sanding resin will work fine (it is just not as strong as lam resin because it has been thinned a bit with wax solution, since the box is pretty much set already, it is not that big an issue). You can take some good tape (like blue 3m) and roll it in the length direction (like a snake shape) with the adhesive side out and stick it around the router cut. This is an overflow barrier. Fill the route so the resin flows out of the cut and to the tape line (the fcs overflow strips work even better than tape, but tape will work). This ensures that you fill the route cut all the way up. As far as your fin goes, it really depends on the shape of the board. If you have a wide tail you might want to think about a longer fin. If you have a pulled in/narrow tail you might want a smaller fin. I am sure if you post some dimension, some of the more knowledgable can help you get that worked out. Good luck.