"But life is for learning." - Crosby, Stills and Nash, Back to the Garden.
I'm not the Board Lady. As my longtime brother firefighter MikeyC would say..."you're not even a pimple on the butt of the Board Lady." That being clearly understood I refer back to my opening sentence.
By way of review, the above picture is the original ding.
I solicited the help of my friend Andy who is handier than I but who had never worked with the situation, i.e. a ding in a pvc foam sandwich eps core construction surfboard. He had some materials but I didn't want to bum everything off him so I bought the above materials for this repair and for future repairs.
Prior to going to Andy's house I sanded and prepped the damaged areas and filled them with Surftech ding dough. It took much longer to cure than stated on the packaging. Once cured I sanded the excess. The ding dough is brown and ugly. I thought I had all the cracks and voids filled, but I discovered water leaking out of one of the pin holes so I decided it needed more "patching," therefore the trip to Andy's house.
At Andy's we cut a piece of cloth to cover the bottom ding. The top ding was small so all we did with that one was to "paint" a layer of sun cure epoxy on it. Later we sanded and painted it. For the bottom ding we used the epoxy repair kit and mixed resin and catalyst. We taped off the work area and saturated the cloth with a small brush. It took a long time to cure because it was a very cool day with cloud cover. We waited for it to harden, sanded it, taped the area off again and painted it with white Surftech spray paint.
The above pic shows the results after painting and finish sanding with 3200 wet sandpaper. Not very pretty and it still leaked a drop of water after surfing. Andy and I think that we did not adequately wet the cloth with resin, and that it did not cure properly because of the weather.
I was concerned that water was going to penetrate the eps core but NC Paddle Surfer said that the water was from "the void left by the dent." But I didn't want any leakage at all so I decided to repair the repair. Because I didn't like the Surftech ding dough I bought a tube of Brudda Brand ding dough after reading about it on the Stand Up Zone forum. I used a very small amount and pressed it into the uneven surface of the repair. I thought I had pushed material into every crevice and hole.
When finished I sanded it smooth and prepped it for painting. It looked smooth and entirely sealed when I noticed that there were two pin holes that had not been filled. Being the meticulous craftsman that I am, I said, "screw it!" And proceeded to the painting step.
I taped off and painted the area. I used Surftech spray paint in a can and hoped for a good color match. Up close you can see that the colors don't match. A real repair person would probably mix their own color and apply it with an airbrush. The first time we painted the surface we had trouble with paint runs. So this time, I actually took my time and put a "dusting" of paint on in six or seven successive layers.
No runs and it looked pretty good except for one pin hole. I thought, it can't possibly leak...The garage was cold by then so I closed the overhead door and set up a propane heater about six feet from the board and repair area. I thought a little heat would help the paint set up faster.
Much to my unhappy surprise, a couple air bubbles caused by off gassing (I think) developed in the repaired area. At first I thought it was water, but since eps off gases so easily I think it must have been the application of heat too close to the board. In fact the underside of the board trapped some heat from the propane heater and it was very warm to the touch.
After the air bubble collapsed and everything cured I waited a couple days before final sanding with 3200 wet sand paper. In those several days I surfed for about four and half hours. The repairs are water tight and I haven't seen any water leaking out. In this final picture you can clearly see the big pin hole, some satellite pin holes and the paint color differences. C'est la vie. (I refer back to my first sentence again.)
I'm glad I got the chance to work with the material and learn more about it. If I had it to do all over again, I would just make sure all the water was out of the damaged area. Knowing that there was no core penetration, I would sand and prep it and fill it with Brudda ding dough. After that was cured I would sand and smooth and take it surfing. If no leaks developed I would prep and paint it. There was really no need to use the cloth for this job, but it was interesting working with it. I would be more careful about using heat.
Summary thoughts: 1) It's too bad the ding dough isn't white then I could just use the dough for most repairs and go on my merry, lazy way. But the second you sand to prep, you get right down to the carbon gray color under the paint. 2) While pvc foam sandwich construction makes for a very durable board and undoubtedly is tougher than p/u or epoxy construction (especially when it comes to reducing dings from your paddle bashes), it does receive damage. The worst aspect of repair is having to paint it. 3) Dings that penetrate the eps core would necessitate extra work and more research, but repairing them could be done by an amateur. 4) If the repair restores the structural integrity of the board then all is well. Unless I get a lot better at the cosmetics, before I sell the board I'd take it to a professional to clean it up and make it pretty.