Air bubbles under the tape

[Cecile]

Moondog's plastering job is going well, although for some reason he's developed air bubbles under the tape (paper). It may not be noticeable once it's completely dry, and this wall will be covered by bookcases so I'm not too fussed.

He was using powder, not premix, and I think he had some issues with the mixture going off too quickly which may be the cause.

What causes the bubbling of the tape?

[mike_perth]

Hopefully Rod will chip in here but with my tape joints done by hand and not a tape gun Ive found they bubble if you dont put a bit of taping compound in the joint before applying the tape. Dont know if thats how it was applied but maybe worth checking that.

[Moondog55]

Heck, CC didn't ask me.
i know what caused the bubbling, it was and old opened bag oo of base-coat which had started to go off so I added a touch of citric acid to slow down the hardening, it was still working the gas out when I put the tape in the bedding mix.
trying to renovate and do all this in a hurry is the problem that's all. Won't show when the sanding is finished, just makes the sanding a little more intensive

[sundancewfs]

I had a couple of bubbles under the tape that I just cut with the stanley knife and squeezed down with the next coat.

[Rod Dyson]

Sorry guys I have been out of it for a while. Busy with 30 units.

Even we get the odd bubble in paper tape and often they don't appear until another coat is applied (or paint). The reason is that the new moisture causes the tape to swell and lift away as it has not adhered to the mud. Simply cut around the bubble and remove the tape and patch over.

Providing its only 3 or 4 cm long there is no need to re tape. It is caused buy a dry spot in the mud when taping usually because it is too thin on a warm day.

Cheers Rod

[Moondog55]

Thanks Rod, I did as Sundance suggested ( I already knew this ) but the problem was mainly caused by my trying to save a dollar and using a bag of base-coat well past its use-by date.
It was more important to get the job done than to do a really good job, I'm not happy with it but we have seen worse jobs done, some of those by so called "Professionals" and a coat of matt paint hides a lot of small blemishes