DIY Dictionary: Setting Compound

Photo: Courtesy of USG

What is Setting Compound?

Setting compound is a powder—primarily plaster of Paris—which, when mixed with water creates a fast-setting material used to fill gaps and cracks in drywall. There are a wide range of setting compounds available, each accompanied by a number—5, 20, 45, 90, 210, etc.—that relates to how many minutes it remains workable before it starts setting or hardening. There are “easy sand” and standard versions available. Check out this expert advice on choosing the right joint compound.

Pros often use “5” to “20” minute compounds since these fast setting compounds allow them to fill large gaps around electrical boxes, in corners and between sheets, and then move quickly on to applying the joint and topping compounds for the final coats. Rookies should use fast setting compounds with care; they have a short working time and any resultant ridges, blobs and imperfections may require hours of sanding in order to smooth them out. Here’s why it’s worth it to use setting-type joint compound.