small cracks in joint compound JOINTS

cody21

I used the fiber mesh type of tape in all joints of our green board. A couple of the joints have a few very fine/small cracks (like 2" in varios places) ... I sanded over them and the cracks are sort of gone (maybe from the dust settling into the cracks?) ... what causes these cracks? I used a corner trowel to apply the compond. Should I just apply another coat? or wil the Primer & final painting fix this? I used the Westpac All Purpose Joint Compound that comes pre-mixed in a tub.

Thanks !

Gary in WA

Fiber mesh tape was made for rapid-set (chemical dry, not air) compounds- 20 minute, 40, 90. I would have used paper tape with your mud. Green board has been proven unacceptable for use in wet locations. Most, if not all jurisdictions won't allow it there. As you probably know, since you are painting it. You could apply another coat, total of four, to try and hide it.
When you say corner trowel, inside corner? That is some extra work to get it to cover mesh. Try paper in the corner or a pre-creased rigid one, you'll be amazed at the application difference. Be safe, G

cody21

Thanks for the reply... These are walls in the bathroom area - not the actual WET shower area. Our bldg. code states this is acceptable. we used Cement Backer Board in the actual Shower area where things will get wet. And yes, these are INSIDE corners that I'm referring to... The cracks are so thin that I won't be pulling ot the Mesh tape and re-doing it... I'll just apply the Primer and 1 or 2 coats of Paint and hope for the best... But I was most amazed to see the cracks in the first place and curious why that happened. I'll use Paper tape the next time for Inside Corners.


Thanks again.

bjbatlanta

As GBAR said, setting type compound MUST be used at least for the first coat over mesh tape and ALWAYS use paper in the corners. You don't have to remove the mesh, just put a layer of paper over it and finish. If you don't, it's likely this will be a recurring problem and may end up more than just "fine" cracks as you go through heating/cooling seasons and your lumber "moves"....

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cody21

Thanks .. will do. I haven't painted yet, so now is the time.