Hairline crack in joint compound

elbee

Hi all,
We had terrible leaking in our house and ended up tearing out a lot of drywall. We also did a repipe so we cut a lot of holes in drywall. I just did all the patching and I used drywall tape and joint compound. I am at the sanding stage and I noticed some very fine hairline cracks especially where the tape is over the painted wall area. The tape is not bubbling at all. Did I install the tape wrong? Should I redo it or just add more joint compound. I didn't sand the painted area before I layed down the joint compound and the tape.

joed

Possibly not enough compound. Can you post pictures?

elbee

I tried to take pictures but they didn't come out. The cracks are very hard to see. You can really only see them when you shine a light on the wall at an angle.

AtlanticWBConst.

Did you use mesh taper? or paper tape?

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elbee

paper tape

elbee

I managed to get a decent picture of one of the cracks. I put a nickel in the picture just so the camera would have something to focus on. The red arrow points to the crack and it runs horizontal. You can also see the picture here because I think it gets compressed otherwise:

http://www.cobblehillpartners.com/test/wallcrack.gif

Attached Thumbnails

 

AtlanticWBConst.

Could that be the edge of the paper tape lifting?

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elbee

Well, it is the edge of the tape, but it is not really lifting per se, because when I push on it, it doesn't move. But, I don't really know if I should rip it out and start over or just put more joint compound on top of it. I just don't know what it should normally look like.

AtlanticWBConst.

You can pry that tape edge open a little. Then, using a taping knife, push more compound under it. Wipe the tape flat, and re-coat.

Often, if you over-wipe the tape (compressing and pushing the compound out), too much compound may be removed. This results in lack of adhesion, and air bubbles.
That could have been what happened. You may have over-wiped the paper tape. If there is not enough compound (which acts like a glue/adhesive), then the tape will separate from the sheetrock. That appears to be what has happened to that edge.

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elbee

Ok. Thank you!

joed

If that is the edge of the tape you need more compound to cover it. Don't sand so much. Tape needs to be covered with mud.