board finish over WBA

[trowelmonkey1]

so...had a couple of walls to overskim last week, painted with a silk type paint so i used WBA to prime them and decided to give board finish a go as there would be very little suction.

so far so good, i thought, until i laid it on...looked like a flamin' aero advert, never in my short skimming career had i seen so many bubbles!

hoping someone can tell me why, guessing it's down to a combination of the texture of the WBA trapping air and the lack of suction on the walls?

 

[roy c]

Why did you use wba instead of pva TM? Some times I throw a few hand fulls of sand in with the pva and brush it on , you have to dig the brush right down into the bucket to get some sand on it and then paint it on. This will usually give you a good key on most surfaces. Also you can mix the sand in with sbr and do the same .You will get patches on the wall where the sand is quite thick , but don't worry about that as long as you have got some grains of sand on the wall..As for the bubbles, was the wba wet when you laid the b/finish on?

 

[NickB_99]

so...had a couple of walls to overskim last week, painted with a silk type paint so i used WBA to prime them and decided to give board finish a go as there would be very little suction.

Hi TM1.
Our house (I've been very slowly working my through) has a shiny/silk type paint throughout (in lovely yellow and sky blue! )

So far, has been ok with PVA alone and multi-finish.
Suction seems nil as PVA seems to be either dry or wet and nothing in between, but has been ok to cover and still on 12 months on in some rooms.

 

[Micilin]

Perhaps you could let your first coat pick up (go off) a bit more before second coat.

It also should be closed in farly well and flattened.

A thick coat of finish will tend to bubble/ripple etc more -how much is going on?

Maybe you are trowelling too much while it is still too soft, in an attempt to get rid of the blisters -a hard rub when it is nearly gone off will be more effective?

Anybody else?

 

[trowelmonkey1]

hello chaps!

well, i used WBA because it's ready out the tub made for the job, never used the sand in PVA method but keep meaning to Roy, just easy to grab a couple of tubs of WBA when i'm in wickes

anyhow, bubbles appeared almost straight after laying on Mic, no trowelling had happened at that point, i left it to pull right in and then trowelled it which got a lot of the bubbles out, the second coat then went all cheesy, seperate issue and suspect it was because the first had gone so far before i went on top of it, anyhow, got it done with a third emergency topping but all could have been avoided were it not for those pesky bubbles.

 

[Micilin]

I have noticed blisters on Bond it /wba , and used a hard rub near the end of the set to get rid.

Another idea is to have a go with a sponge float to take them all out, and lay it down after. Worth a try on a small area to get the feel of it first.

 

[trowelmonkey1]

thats a good idea Mic, have one in my bucket just waiting for a job to do.

thought i'd try board finish as it was going to be a low suction substrate, should've stuck with multi and just waited for it i suppose.