Our site works best with Javascript enabled.

Need Help? Call
MON-FRI 8:30am-5:00pm Central
PM21 Mastic Sealant
Virginia KMP PM21
1 Gallon Bucket of Thermal Mastic Duct Sealant

Product has been discontinued.
Please call us for a suitable alternate product.

Mon - Fri 8:30am - 5:00pm Central

Thermal mastic compound is used to professionally seal duct work, and in any application in which enhanced surface to surface heat transfer would aid in system or component performance such as expansion valve and thermometer sensor bulbs.  Sealing duct work saves money on heating and cooling costs by preventing air leaks.

Also available in a 7.5oz tube and 5 gallon bucket.


  • Stable between -50°F to 220°F (-46°C to 100°C).
  • Increases heat transfer between surfaces 4 times over mechanical mounting alone.
  • Replaces solder for heat transmission.
  • Available in 3 convenient sizes.

Your Order
Ways to Order
See Order Status
Modify or Cancel Order
Missing Order Item
Damaged Shipments
Warranty Claims
View Quotes
Request Custom Equipment
Technical Support
Learning Center
Instruction Manuals
Contact Technical Support
Shipping Policy
Return Policy
Scratch-N-Dent Policy
Volume Discount Policy
Privacy Policy
Website Terms of Use
About Us
Customer Reviews
(800) 865-5931
Monday to Friday
8:30am - 5:00pm Central
  Mailing Address
1901 N. Clybourn Avenue
Suite 200
Chicago, IL 60614
[email protected]
or Contact Us Here
(425) 928-2455
© Copyright 2002-2014, Alpine Home Air Products. All Rights Reserved. A Todd Arthurs Company, Inc