Denzo tape "stuff" appearing through wall

[davo84]

Hi all,

I had some work carried out in the bathroom and the plumber sealed a couple of pipes with denzo tape and then plastered over them.

After about a day the plaster was showing some traces of "green stuff" permeating from the denzo tape, and even after a month and a couple of white emulsion coats is still visible and expanding (even though a bit slower). The plumber claimed that he sealed the plaster to make it paintable (although I wasn't there).

What should I use to get a decent paint finish?

Thank you in advance,
Davide

 

[joe-90]

Are you sure that there isn't a slow leak?

 

[davo84]

The pipes have been uncovered for a couple of days and there was no sign of leaks, but I can't exclude that.

the thing is that the layer of plaster is very very thin, and it does not look like a normal leak, nor seems damp.

 

[davo84]

Hi,

bumping up this post, as I waited long enough to understand that there is no leak. The emulsion got this tight area of yellowish colour (the denso tape permeating).

What's the best way to prepare it for painting?

 

[joe-90]

Oil undercoat is by far the cheapest.