Wet Tack and Dry Tack of Latex Based Adhesives

Manufacturer: I am new to latex based adhesive technology. Please explain the difference between wet and dry tack and how to improve them.

John Woon (Senior Latex Consultant): "Wet tack" is the ability of the latex to hold to layers of materials together before drying. This depends a lot on the nature of the substrates concerned.  A solid impermeable substrate is more difficult to adhere to compared with, for examples, a porous textile or paper board.

Other factors involved in ensuring good wet tack are:

1) Surface tension and wetting - A good wetting with low surface tension is required for the initial spreading and wetting of the substrates.
2) Total solid content - Higher TSC is required for higher initial tack.
3) Mechanical stability - Lower mechanical stability is needed for the quick development of the wet tack.
4) Types of stabilizers used - rosin acid soaps are preferred to fatty acid and non-ionic soaps.
5) Nature of polymer - Lower Tg is preferred to ensure the polymer is soft enough for better particle-to-particle integration and  film formation.

As for "dry tack", I have already covered this in my earlier posting om "Nitrile Latex Adhesives" below.