I’m not 100% sure that they have the data in a technical format but I will ask.
I will ask the scientists but be warned, I might not be able to spell some of the words they use, never mind understand them.
Made me chuckle!
Sorry, when I said 'technically', I didn't mean to the extent of scientific formulas and test tubes
I just meant I would like to know in plain english specifically WHAT is actually happening that gives rise to blebs - what is the mechanism, rather than anecdotal explanations of 'tends to happen when too wet or applied too thick' etc.
With regards to your question on blebs on your bonding, how long are you leaving it before you skim it?
Varies. Sometimes left overnight before skimming, sometimes just a couple of hours, sometimes half a day. Of course it doesn't bleb everytime, but if I had a better understanding of exactly what causes blebs, then it'd be easier to consistently avoid them, rather than getting caught out now & then. I bet most spreads have had to deal with them, occasionally, and no one likes having extra hassle in their day.
The vermiculite in Bonding would not be effected by the application of a finishing coat once it has set.
No, I meant the other way around. Vermiculite is randomly dispersed throughout the applied area of bonding on a wall, some chunks of vermiculite will lie deeper than other chunks. The shallower chunks will have less gypsum (from the bonding coat) between them and the next coat of skim. Is it possible that this could make those tiny areas less absorbent - i.e. pull less moisture out of the subsequent skim layer?
I'm only guessing, and I could be a thousand miles out.
All I'm asking is for a better understanding of what actually causes blebs. Maybe the BG boffins aren't sure, or maybe they do have a useful answer. I can only ask
In the meantime, I will bear in mind what you've mentioned about wet substrate and thickness