Everyone has different methods and preferences when it comes to the mud they use for taping joints. This article is meant to give you some basic pointers in choosing the right joint compound to run through your automatic taper. From years of experience and field research we recommend using a full weight all purpose joint compound such as USG All Purpose (green lid), or ProForm All Purpose (black lid), and here is why:
High glue (adhesive) content.
When taping with automatic tapers, you often need to thin your compound down significantly with water, especially when taping corners. The more glue you have in your taping mud, the better your tape will bond to the wall, even when thinning down the compound. This will mean less chance of blisters, and less chance of tape peeling.
Joint compound that has a high glue content also tends to have more "slip". This means that the compound will slide easier behind the joint tape, which is especially helpful when taping corners. If there are any small dry areas on the backside of the joint tape, the mud will slide behind the tape more easily when it has a high glue content. Joint compounds with high glue content also tend to move faster and smoother through the tube and head of the automatic taper.
Joint compounds with high glue content tend to have a longer working time than softer lightweight compounds. This means you will have more working time before the mud skins over and becomes more difficult to work with. This is especially important when it comes to rolling and glazing corners. Longer working time also means that it will take longer for your taper to get dry and crusty!
There are some things to be aware of with using a full weight all purpose joint compound, especially when you are thinning it down.
Taping joints with full weight joint compound that has been thinned down can leave you susceptible to cracks where the joints are offset, have open gaps, or when the joint tape gets wiped too tight. This is because full weight compounds have a tendency to shrink significantly, which can result in a void behind your tape after the mud pulls into the joint. We highly recommend that you pre-fill any open or offset joints with a setting type compound prior to the taping process to prevent cracking.