Did the shellac contain wax? It did unless it said it was dewaxed or stated it did not contain wax.Customer didn't want mineral oil so we decided to spray a urethane on it. They are not using it as a cutting board.
My question is the top is maple and the urethane is a general finishes water base. So I put a coat of shellac sealer first then sanded lightly with a 400 grit. It's smooth but not like I had it before.
If I was to sand it again with a 220 to bring it smooth again would I be ok to spray the water base or would the grain come back up after sanding the shellac sealer. Wondering if it would be soaked in enough that I wouldn't have to worry about that now?
Urethane, oil based or water based may not adhere well to any finish which contains wax.
Water based finishes takes days to fully cure. If you sanded too soon, you may get portions which come off and portions which are rough due to not being cured.
If this was my project, I would sand back to bare wood and just apply General Finish Salad Bowl Finish. I have been very happy with this product. I apply with lint free cloth, cures overnight. Very light sanding between coats, 400 grit. It leaves a very nice smooth finish and should last like urethane.
I have sprayed water based poly. Goes on easy. I get frustrated with drips. Not easy to prevent all drips. Worst part is needing to wait so long before sanding or attempting to remove the drips.
This is a decorative board I completed back in late July. I applied 3 coats of the Salad Bowl Finish by the lint free cloth/hand method. No runs, no dust, cures overnight. I did buff the final coat with Tripoli compound.