ASI 502 100% RTV Silicone Sealant, White, 2.8 oz Squeeze Tube

White ASI 502 is the same High Performance 100% RTV Silicone as ASI’s clear and black versions, pigmented to blend with white surfaces. Use it where a clear bead would let the joint or backing show through, or where a white line simply looks cleaner: tub and shower surrounds, porcelain fixtures, white appliances and refrigeration cabinets. The 2.8 oz squeeze tube is applied by hand, with no caulking gun.

Key features

• Mold and mildew resistant, per ASI, which suits kitchens, baths and other damp areas
• Resists UV, weathering and yellowing; passed 10,000 hours of QUV testing (ASTM G154)
• Fast skin (about 10 minutes) and a 24-hour cure per 1/8″ bead at 70°F and 50% RH
• Bonds ceramic, porcelain, tile, marble, glass, most metals, PVC, most fiberglass and solid-surface countertops
• ASTM C920 Class 25, Type S, Grade NS; federal specifications TT-S-01543A and TT-S-00230-C
• ASI’s data sheet for ASI 502 lists NSF Standard 51 (incidental food contact) and FDA 21 CFR 177.2600

Where to use it

Bathrooms and kitchens are the obvious fit: sanitary seals around sinks, tubs and fixtures, and countertop-to-backsplash joints. ASI also lists plumbing, appliance manufacturing, refrigeration units, walk-in freezers, HVAC, ductwork and formed-in-place gaskets, so white 502 works on white appliance housings, white freezer panels and painted white enclosures as well.

How to use

1. Cut out old caulk and remove the residue, then wipe with 100% isopropyl alcohol or acetone (per ASI). Never use mineral spirits or other petroleum-based solvents.
2. For a straight white line, mask both sides of the joint with painter’s tape.
3. Squeeze a steady bead into the joint, pressing the sealant in rather than laying it on top.
4. Tool within about 10 minutes and pull the tape right away, before the skin forms.
5. Let it cure, about 24 hours per 1/8″ bead and longer in cold, dry rooms, before the fixture goes back into use.

Compatibility and cautions

ASI says not to use ASI 502 on porous surfaces such as concrete, mortar or brick, and it cannot be painted. It bonds to “some plastics” only, so test first. Because it is an acetoxy silicone, ASI warns it is corrosive to sensitive metals when confined, which rules it out for electronics. Expect a vinegar odor while it cures and keep the room ventilated; the SDS does not classify it as hazardous under GHS. Read the label and the documents on our technical documents page.

Choosing between ASI 502 colors and sizes

Pick by what surrounds the joint: white for white surfaces, clear ASI 502 when the bead should disappear, and black ASI 502 for dark trim and metal. For long runs, the ASI 502 10.2 oz cartridge (clear) goes in a caulking gun. If the seal is on electronics, switch to neutral-cure ASI 388. See all ASI sealants.