Dry Time Between Seal Coat and Flood Coat
4-10 hours is optimal, however you can wait as long as you like to apply the flood coat with no sanding required.
When re-coating within a 4 to 10-hour window no surface preparation is needed. The layers will bond together as one. Past 10 hours, you will need to lightly scuff the surface with 220 or 320 grit sandpaper. After scuffing, you should wipe off the surface using a clean rag with denatured alcohol or acetone. Do NOT use paint thinner, aka mineral spirits. The wipe down process with the solvent should be done with a clean rag that will not leave any lint on the surface. Continue cleaning until all sanding dust has been completely removed. You are now ready to re-coat. Don’t worry about the sanding scratches. The next pour will fill in the scratches and it will look like crystal clear glass again.
DO NOT USE A TACK CLOTH, this will leave oils on the surface causing the epoxy not to adhere or leave fisheyes.