GE Supreme Silicone Kitchen & Bath is a good fit for flexible, intermittently wet joints around tubs, showers, sinks, tile and countertops, as long as the bead never needs paint. It is 100% neutral-cure silicone rated ASTM C920 Class 50, and it is not paintable. This page covers only that formula. GE’s Silicone 1, Advanced Silicone 2 and paintable hybrids have different cure and use directions.

What GE’s data sheet confirms

  • Chemistry: 100% silicone, neutral cure, low odor.
  • Rating: ASTM C920, Type S, Grade NS, Class 50, meaning ±50% joint movement. GE says it can span gaps up to 5/8 by 5/8 inch.
  • Sizes and colors: 10.1-ounce cartridges in white, clear and almond, and 2.8-ounce packs in white and clear in the U.S.
  • Coverage: a 10.1-ounce cartridge runs about 51 feet of 3/16-inch bead, or about 13.7 feet of 3/8-inch bead.
  • Cure: tack-free in about 30 minutes and cured in about 24 hours at 73°F and 50% humidity. Cold or dry air slows both.
  • Service temperature: -60°F to 400°F once cured.

The 30-minute water-ready claim has conditions

GE’s 30-minute claim needs three things: a bead no wider than 3/16 inch, at least 65°F and at least 50% relative humidity. If any of those is missing, GE says to keep water off for eight hours. In every case, don’t touch or clean the bead for 24 hours. A wide bead in a cool, dry bathroom in winter needs the longer wait.

Where GE says not to use it

The data sheet rules out:

  • joints that will be painted;
  • underwater or continuous water contact, and aquariums;
  • food-contact uses;
  • structural repairs and spackling;
  • bedding under shower-door tracks;
  • frozen or contaminated surfaces, and very acidic or alkaline surfaces;
  • galvanized metal, mirrors and other special coatings, unless that product’s manufacturer approves.

Natural stone, plastics and coated fixtures are listed in general terms. Test a small hidden spot and check the fixture maker’s instructions before sealing a whole run.

Preparation decides the result

Remove all of the old sealant. Fresh silicone won’t bond reliably to old silicone, soap film or loose material. Clean and dry the joint, tape the edges if appearance matters, and cut the nozzle to the bead size you need. Tool the bead before it skins over. Caulk can’t fix a loose tub, cracked grout or water getting in behind the tile. Fix those first.

The “mold-free” claim applies to the cured sealant itself. GE’s own footnote says regular cleaning is still needed, because soap and other residue can grow mold on the surface.

Buying check

Look for Supreme Silicone Kitchen & Bath on the label, not another GE silicone, then match the color and size. Choose a paintable or structural product if the joint needs either.

This review is based on GE’s documents. No product was applied or tested.

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