G/Flex is pretty close to that color of the bottom of the canoe, it dries hard and is sandable. I wonder if a light sanding with a 1/4 sander (maybe test 180 grit or higher) will knock down those spider cracks enough that the new coat of shellac will fill them in.
I have never done shellac, but I’ve read where 3 light coats sanded with 400 grit in between coats leaves a nice surface.
Thanks Robin, I guess the gflex is ok as long as it doesn't contact the wood? I sanded the whole bottom with 220 and it seemed to knock them down a bit. I didn't sand right down to the filler, figuring it's better to under do it than over do it. You don't think the spider cracks can be in the filler do you?
“You don’t think the spider cracks could be in the filler do you?”
To be honest, I don’t know. I have never really seen a wood canvas canoe that has been shellacked up close, but then I don’t remember ever seeing filler have spider cracks.
There is lots of discussion about Shellac on the Wooden Canoe site and maybe Fitz might chime in on your thread, he has some experience with it. In one thread he mentioned making your own shellac vs. using what could be old product on store shelves to prevent cracks, and he suggested light coats vs. a thick coat.
I wasn't sure about the spider cracks, but after closer inspection they are most likely in the shellac. I did some test sanding last night and determined that there was still lots of shellac on the hull. My plan was to sand it down until all of the spider cracks felt smooth (some still had a rough feel) and redo it. I decided to just use up what shellac I had left in my old can and put on one coat and look at redoing it at the end of the season.
I'm no longer concerned about the planks showing through, (it is what it is) the chalkiness or the spider cracks. One of the good things about shellac is that it is easy to apply and if your results aren't optimum you can hopefully get it right the next time. I've already applied the shellac and will give it a light sanding with 320 grit and then apply a wax.
I'm not sure if the wax protects the shellac. I think it does, but for all I know it could make it break down faster although I didn't notice any negative effects on the original shellac.
As far as the age of the shellac, there is a lot number on the can that a customer service rep at rustoleum told me how to interpret.