How do I seal fabric patches or cloth before embedding them in epoxy?

Fabric darkens when epoxy soaks into the fibers, so patches and cloth pieces must be fully sealed with a non-porous barrier before any epoxy goes on. Mod Podge is our recommended sealer. Apply several light coats to all sides of each patch until it is fully sealed and no longer absorbs moisture. Once completely dry and smooth, adhere the patches and apply the UltraClear Bar & Table Top Epoxy seal coat and flood coat as usual.

Thick or heavily embroidered patches may need a stronger, more complete seal than Mod Podge alone. Some customers report good results with clear spray acrylic or polyurethane sealers. We have no hands-on experience with those, so test on a spare patch first and use them at your own risk.

If a corner lifts above the cured flood coat, there are two options. To encase it, pour more 1/8" flood coats: sand the hardened epoxy with 220 to 320 grit, clean off the dust with acetone or denatured alcohol, pour a flood coat, then a second after 4 to 6 hours have passed, without sanding again. Or sand or cut the raised corner level with the surface, then spot fix it: sand and clean, brush on a little epoxy, and smooth the strokes with a heat gun. Spot fixes can leave seams where the new batch meets the old; a full flood coat is the most seamless option. We haven't encountered this issue before, so expect some trial and error.

Mod Podge: https://www.bestbartopepoxy.com/collections/tools-supplies/products/mod-podge