Duct Seal Putty

RTC# 79511, RTC# 79526,

A gray, permanently soft, non-toxic compound which will adhere to most clean dry surfaces. It will not adversely affect other plastic materials or corrode metals. It also has no adverse effect to human skin.


Rainbow Duct Seal Putty is used primarily by the building and specifically by the electrical trade to seal around electrical boxes, flashings, and service mast entries, etc. It can be shaped by hand to any form and reused if necessary. It has countless other applications in the refrigeration, heating and cooling, plumbing, and metal fabrication fields as well as being an excellent general purpose sealant around the home. It may be painted immediately after application and will not bleed through the dry paint.

Rainbow Number Container Ordering UOM Units/Case Case Weight Case Size
795115 lb PackPack10 Packs50 lbs12" L x 12" W x 9.5" H
795261 lb PackEach50 Packs50 lbs12" L x 12" W x 9.5" H

FDA Approved: As listed in CFR, Title 21, being composed of ingredients acceptable for packaging and transporting food.
U.S.D.A. Acceptable: Chemically acceptable to the U.S.D.A. for use in meat and poultry processing areas under Federal Inspection.
Dielectric Strength: Approx. 200 volts per mil (ASTM D149-64) or 10 KV.
Chemical Resistance: Excellent resistance to water, alcohols, mild acids and bases.
Vehicle Bleedout: None.
Non-Corrosive: Will not corrode Metals.
Non-Irritant: No irritation to eyes or skin as listed in CFR, Title 16, “Appraisal of the safety of chemicals in food, drugs, and cosmetics.
Paintability: Yes.
UV Inhibitors: Contains a pigment that serves as a UV stabilizer. The pigment absorbs the UV light and transfers it to heat, lengthening the life of the polymer bonds that make up the sealant. Anti-oxidant inhibitors are present that also help prevent UV degradation. The base polymers used are very stable against UV effects so there are inherent natural properties for this resistance as well.

Properties Test Method Value
Base N/A Non-drying synthetic polymers and oils
Fillers N/A Saturated mineral fillers and other inert ingredients
Specific Gravity ASTM D71-72 1.65-1.7
Cone Penetration ASTM D217-52T Load of 300 gm..5 sec. @25°F; 100-115 mm/10
Temperature Usage Range 24°F to 120°F Recommended
Temperature Tolerance Range -30°F to 175°F Will not slump at 275°F