Reconstitute Dried Spackle Step 1: Water. Add a liberal amount of tap water. Step 2: Mix. Break up the dried clumps and mix it with the water just a bit. Step 3: Nuke. Put the jar in the microwave for 20 seconds. Step 4: Nuke It Again. Put it back in the microwave for another 30 seconds. 2 People Made This Project! bluehowlite made it! 9 Discussions. Click to see full answer. People also ask, what do you do with dried out spackle?Revive dry spackling paste with water. Spackling compound is a product used for patching holes. It resembles a slightly off-white brand of frosting or toothpaste. You use it by scooping it out on a putty knife and smearing it into holes, cracks or anywhere on drywall or sheetrock that needs a smooth flat surface.Furthermore, does spackle dry out? Spackle is used frequently to patch holes and give drywall an even surface. After spackle paste is applied, it will harden and become part of the wall. It is no surprise that the paste will eventually harden in its container, as well. If this happens, you can add water to it to loosen it up so it can be used again. Keeping this in view, can you rehydrate joint compound? While you can rehydrate mud, the rehydrated stuff you make will not perform acceptably. The reason is in the binder, the stuff that makes it harden and stick to the wall.How long does spackle last? Average Shelf Life Most wet compounds are rated for around nine months to a year so long as the compound is kept in the right conditions. Dry compounds have a similar shelf life of around a year so long as the proper storage methods are used.