If you use tape for sealing ducts, pressure sensitive tape should be
rated UL-181-AP. That is in the new International Residential Building
Code. ShurTape AF-100 is the one I normally use. It has an acrylic
adhesive instead of the rubber based adhesive that regular duct tape
does. It should be rubbed down with a squegee like you use for applying
body putty. It is called a rub down tool. That helps the adhesive to
cure and gives better adhesion. UL-181-AP tapes have the brand name
ant the tape model number written on them. It MUST be at least 2-1/2"
wide It has UL-181-AP rwitten on it in block letters. It also has the
last test date on it as well. It will normall have a white adhesive
protected by a white release paper. If it does not have all of those
features, it is not the correct tape. There are 5 brands with 5
different tape model numbers that are acceptable to code and the UL..
Fasson also makes one as does Ideal. I'm not sure of the other two
brands.

Stretch