Plaster not adhering to plasterboard?

paperclap

Hi all,

I’ve just boxed in all my pipework with battens and plasterboard. As the walls were out, there are a few gaps larger than there should be… so prior to taping and plastering, I’d thought to do some pre-filling.

But, this MultiFinish is just not adhering as it should. It’s “pulling” off the board. Why? And how can I rectify this mess, so I can plaster successfully over the top?

Definitely not got too “dry” a mix!

Thanks.

grumbler

Is this a corner or a plane?

And both the plasterboard and the MultiFinish look odd to me. A new plasterboard normally has a smooth surface (paper or plastic film). Finishing plaster is normally pinkish. And it shrinks a lot and cracks when drying, so not really good for big gaps or thick layers. This doesn't explain your “pulling”, but generally for filling gaps it's better to use 'joint filler' (it's white) at the same time when you do tapping.

fenwick458

how old is it? is it a brand new bag of multifinish?

paperclap

The bag of MultiFinish is brand new. Literally just bought it a few days ago.

Sure… but you can use MultiFinish for this purpose. Why wouldn’t you be able to?

This is an internal corner.

FreeBear

paperclap said: The bag of MultiFinish is brand new. Literally just bought it a few days ago.

Check the date on the bag. It is not unknown for some suppliers to push out old stock on unsuspecting customers.

When using plasterboard, I'll often slap a fillet of jointing compound on the edge before fixing it in to place. The excess that is squeezed out gets flattened off with a corner trowel or spatula. Doing it this way ensures that there is a good dollop of compound in the joint. Some mesh tape over the top (some say use paper tape), and then plaster.

paperclap

It’s in date. 03/10/2023!

FreeBear

paperclap said: It’s in date. 03/10/2023!

That doesn't sound right... British Gypsum usually give a self life of just four months from bagging if stored in ideal conditions (i.e. somewhere cool & dry).

breaking_free

I agree with Freebear. Post a picture of the bag please. That dark brown colour looks like a bonding coat plaster to me rather than a top coat of pinkish coloured multifinish.

liberty_lily

breaking_free said:

I agree with Freebear. Post a picture of the bag please. That dark brown colour looks like a bonding coat plaster to me rather than a top coat of pinkish coloured multifinish.

Me too....DH has done loads of plastering over the years and that looks nothing like any of the multifinish I've seen him use. More like the texture and colour of bonding plaster imho.

rob7475

That's not multifinish unless it's been mixed really poorly. Multifinish will never hold in a gap like that anyway. Either bonding or joint filler are what you need.

That board doesn't look like plasterboard either. It should be a smooth surface

paperclap

Thanks for the replies.

It is definitely 100% MultiFinish. See photo.

Though, it is getting a bit weird now. I too think it looks like bonding, as does my Dad! I’ve used bonding before in other areas of the house, and it has the same gritty texture.

I’m not taping and jointing this plasterboard. I’m taping and plastering the entire surface (as the area is too small to achieve a good feathered-in finish, I think).

Several comments on this plasterboard now. What about it doesn’t look like normal plasterboard? Because it has a subtle ripple effect?