Air Bubbles in plaster skim

[Horse Hair]

Hi

Iv'e been plastering on and off now for about 10 years mostly for myself and friends and family though not a plasterer by trade.
Nearly always I manage to do a decent job, or so I am told, ranging from replacing and skimming ceilings to rendering walls and finishing.
One problem I encounter frequently is the presence of what look like air bubbles in plaster finish.
These are few and far between but nearly always seems to happen on an scratched undercoat like Toughcoat or Hardwall.
Rarely does it happen when I am applying finish to boards for which I mostly use Board finish or sometime Multi finish.
I have an inkling that it may have to do with how deeply the undercoat has been scratched but I am not sure and that may well be way off beam.

So,I was wondering if any of you experienced plasterers out there have come across this and know of a solution?

thanks
Horsehair

 

[jbonding]

it sounds like your flattening or laying it down too soon let it go before you trowel but if it happens you can only get them out on the final trowel.

 

[Horse Hair]

Thanks for your reply JB.
You could well be right about flattening or laying it down to soon.
So you would advise leaving the coat longer before troweling out?
I supposes as I am not a plasterer by trade these answers to problems only come with experience.
I will remember this next time though.

many thanks
Horse Hair