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

ASI 502 High Performance 100% RTV Silicone is the food-grade member of ASI’s acetoxy line: American Sealants Inc. states it meets NSF Standard 51 and FDA 21 CFR 177.2600 and is acceptable as a sealant on surfaces with incidental food contact. That is why buyers look for ASI 502 food grade silicone for kitchens, coolers and food-service equipment. This clear 2.8 oz squeeze tube is sized for touch-ups and short seams, such as a backsplash joint, a walk-in freezer panel corner or a sink rim, where a cartridge and gun would be more than you need.

Key features

• 100% silicone with an acetoxy moisture cure; ASI says it contains no solvents, so it will not shrink or crack
• NSF Standard 51 and FDA 21 CFR 177.2600 (per ASI’s data sheet); also UL Recognized and MIL 46106B Type 1
• Mold and mildew resistant, with resistance to UV, weathering and yellowing
• Non-slump: stays put on vertical and overhead joints
• 25% joint movement (ASTM C920 Class 25); -70°F to 400°F service, 450°F intermittent
• Skins in about 10 minutes and cures in about 24 hours per 1/8″ bead (70°F, 50% RH)

Where to use it

ASI lists countertops, kitchen and bath, sanitary seals, plumbing, appliance manufacturing, refrigeration units, walk-in freezers, HVAC and ductwork. Clear is the color to pick when the bead should disappear against glass, stainless steel, tile or a colored surface. Common substrates include glass, most metals, ceramic, tile, marble, PVC, solid-surface countertops and most painted surfaces.

How to use

1. Remove old sealant, then clean with 100% isopropyl alcohol or acetone (ASI’s recommendation) and let the surface dry. Do not use petroleum-based solvents.
2. Cut the nozzle to the bead size and apply in one continuous pass, between -35°F and 150°F.
3. Tool the bead within about 10 minutes, before a skin forms.
4. Ventilate while it cures; a vinegar (acetic acid) odor is normal.
5. Allow about 24 hours per 1/8″ bead before the surface goes back into service. Strength keeps building for 7 days.

Compatibility and cautions

ASI notes that its acetoxy cure is corrosive to sensitive metals when confined, so keep it away from electronics and enclosed metal assemblies. Do not use it on porous surfaces such as concrete, mortar or brick, and plan the color now: ASI 502 is not paintable. ASI’s food listing is NSF 51 (food equipment materials); it does not list NSF 61, the drinking-water standard, so do not treat it as a potable-water sealant. The SDS does not classify it as hazardous under GHS; use it outdoors or with good ventilation. Data sheets: technical documents.

Choosing between ASI 502 options

Same formula, other choices: white ASI 502 for white fixtures and tile, black ASI 502 for dark trim and metal, and the ASI 502 clear 10.2 oz cartridge for long runs. For electronics use neutral-cure ASI 388 electronic grade silicone; for fish tanks use ASI 509 aquarium silicone, rated aquatic-life safe once cured. More in our acetoxy silicone guide.