The Zinsser product you are using, is it seal coat or just shellac? The reason I ask is this, Zinsser shellac is usually a if I remember correctly a 3pound cut and is not a de-waxed shellac. This can effect bonding of other products. Your mileage may vary, FYI.@Graywolf. Thank you. I've been cutting Zinsser in half with DN to make sanding sealer.
Thank you Jim,I added a PDF with a couple of tables for mixing and thinning shellac in the resources. Download and print the resource to hang in your shop if you like. That's what I plan to do. It's a quick way to get the right ratios when mixing your own shellac.