Hardwall/bonding

[lozmate99]

HI

I am about to plaster hardwall onto brick. The bricks are fairly smooth should I apply some pva first?

Is hardwall the better option over bonding?

I am damn good at plastering over artex, board and onto thistle bond it. I still get a few bubbles when going over bonding/hardwall. This annoys the hell out of me how do I stop it?

Do i need to PVA the hardwall before going over it?

when its just starting to dry out?

when its fully gone off?

Also do I need to score it or can i leave it troweled?

I would really appreciate some advice here!!

Many thanks and happy xmas!

 

[trowelmonkey1]

well there's a lot of questions!

Hardwall is for higher suction backgrounds (brick and block excluding engineer brick which is low suction)

Bonding is for low suction backgrounds and engineer brick.

So assuming your brick aren't engineers bricks use hardwall, but you need to know what type they are, smooth shiny could well be engineers.

no need for PVA first, hardwall wants the suction so don't kill it with PVA, ideally rake ot the joints a little and you can even use a brick hammer on the brick surface to give them a key.

in an ideal world you would float with hardwall in the morning and skim straight onto it that afternoon with just a light spray of water, if it's going to be skimmed later than that then you want to PVA it first, if it's a small section then PVA just before skimming should be fine but PVAing 24hours before skimming will give yu much more time.

you must devil float/scratch it as it setting so that there is a good mechanical key for the skim to hold on to, use a poly float with 4 or 5 screws in the end protruding a couple of mill (devil float) rub the wall up and scratch it at the same time then.

bubble are normally caused by skimming it too soon and water trying to escape can't because of the finish blocking it, if you get some then leave the alone and let the wall pull right in and attempt to flatten them, then top it with the final coat of finish.

think that covers it

 

[lozmate99]

Lovely thank you!