Help needed fairly sharpish!!

[jstrong]

Plastering on top of Celco/Thermalite blocks.

I PVA'd the wall last night and again this morning and have just plastered with bonding which is now starting to drag and dry.

I have some multi finish for the next 2 coat's but shall I wait until the bonding has dried or plaster straight on top now??

Thanks for any quick replies!!

 

[dmplastering]

Plastering on top of Celco/Thermalite blocks.

I PVA'd the wall last night and again this morning and have just plastered with bonding which is now starting to drag and dry.

I have some multi finish for the next 2 coat's but shall I wait until the bonding has dried or plaster straight on top now??

Thanks for any quick replies!!

hopefully you havnt started skimming yet. Wait till bonding has set and completley dark and when you drag your hand down the wall it isnt greasy. A couple hours should do the trick

 

[jstrong]

Thanks DM

The wall in question is a garage door in-fill with concrete lintel above.

The plaster over the block work is fairly dry though not gone dark yet, however, the plaster over the lintel is still pretty wet as lower suction underneath I suppose. Shall I wait until both areas have gone dark?

Thanks in advance.

 

[dmplastering]

Thanks DM

The wall in question is a garage door in-fill with concrete lintel above.

The plaster over the block work is fairly dry though not gone dark yet, however, the plaster over the lintel is still pretty wet as lower suction underneath I suppose. Shall I wait until both areas have gone dark?

Thanks in advance.

Yeah, there is a hell of a lot of suction in those blocks where as there is very little in the lintels. I think you know the answer yourself but yes, wait until both are solid and non greasy.

Are you skimming the whole wall or just patch?

 

[jstrong]

Skimming the whole wall although there is a 1600 x 1000 window in the middle!

Should I pva again once the lot has gone dark and then plaster?

 

[dmplastering]

No need to pva the bonding. The rest of the wall will need pva if you have not already done so

 

[jstrong]

DM

I bonded the whole wall, the bit where the lintel is is going dark, however, the bit where the thermalites are underneath looks bone dry!

I'm fearful tha as soon as I apply the multi finish it will be sucked dry! Shall I pva the dried out bits where the thermalites are underneath and then plaster or dampen it or what?

 

[dmplastering]

It will help kill suction so feel free to pva it. Make sure its tacky before coating onto though

 

[Micilin]

PVA is not much good on thermalites. SBR is a much better sealer. and has to be applied.

that's not much good to you now, I know.

If your bonding is going white dry, I'd be inclined not to chance it.

If your finish sucks in staright away, it will only craze and/or turtle.

To be safe I'd seal it up again tonight and then a fresh coat of PVA in the morning and skim.

Better to hjave it hanging a bit than dry too quick.

Let us know how it goes.

 

[jstrong]

Thanks for the advice.

I pva'd the dry looking parts and waited for it to go tacky which was pretty quickly and then gave it 2 coats of multi finish.

Very pleased with the result so thanks very much to DM & M.

While I'm here can I ask another plastering question?

Where I've plastered a bricked up doorway the finish is a little wavey which is only just noticeable but more so when the sun is setting which shows every blemish under the sun!

For future reference how do you get a really flat finish?

 

[huddsspread]

19 years of plastering......

 

[dmplastering]

As above, come with years of practice. If it was that easy then we would be all be unemployed

 

[DoubleDPlasterers]

As above, come with years of practice. If it was that easy then we would be all be unemployed

Lol.... normally put hardwall on before 11am skim buy 1pm, but yeh those therolites are a pain in ar se for suction.

 

[huddsspread]

The real answer is i suppose pushing hard enough. Whe you put the first coat on, you cant really push hard as you will wipe off the plaster, once its picked up, and you quickly flatten it, push hard. Then your 2nd coat and subsequent trowels, you need to push with a lot of pressure.

Non-plasterers thing its a case of "wiping it on with the edge of the trowell" but its not, you need prseeure to push it flat. Then your final trowell (s) are to polish the top as it will be flat as f@ck from what you have done prior.

 

[joe-90]

I use an 18 inch trowel to get a perfectly flat finish - or even a darby.