mcp6453 wrote:
It looks like I've done something stupid. I used wallboard joint
compound to repair a hole in drywall. Everything went well in the
application and sanding process. Now, a few days later, there are
spider cracks in the compound.

Should I have used spackling instead? Do I have to remove all of the
joint compound (sanding) and start all over?

If wallboard joint compound cracks this easily, what good is it? The
wall is dimensionally stable.

Joint compound shrinks and cracks form -- depending on the thickness of the
material that you applied. That's no big deal.

There are other types of material that you could possibly have used,
depending on what type of hole you started with, etc.

But, since you have the job mostly done, and the only real issue seems to be
the cracks, you can probably just give it another coat of joint compound to
fill in the cracks etc. And, in some cases, you may need a third coat after
that if the second coat cracks. Then sand it and you're done.