andrewro wrote:What constitutes "old" - I've read one month, six months.... This is about four months old.
I suppose it depends on how tight the container was sealed, the dampness and temperature of the storage area, whether it was misted down before storage, etc.
I used four or five month old joint compound during my kitchen rebuild. I had built a brick eyebrow to the dining room and left the scaffolding up for several weeks to ensure decent curing of the mortar:
I couldn't hang the drywall till I removed the scaffolding so that was one of the last steps in the renovation. I'd hung, taped and primed the other drywall months before and had leftover compound from that job. Since I only had three or four short joints to tape I didn't want to buy fresh compound.
What I found was that I couldn't get the compound to knock down as flat as fresh compound. After probably five applications I had a small mountain of compound.which you could plainly see in a side light. I'm pretty good with a taping knife so I knew it wasn't my technique. It had to be that the compound had thickened and even diluting and remixing it didn't help.
I had two choices, both of which involved buying fresh compound: skimcoating the wall or retaping it. I chose the latter because I wasn't sure how well a heavy accumulation of compound would hold up in the steamy climate of a kitchen. I had visions of the tape popping one day while boiling pasta.