Glue and paint

[acepants]

Hi Misterhelpful - i'm in a similar situation.

I'm getting ready to paint the underside of my cement/asbestos garage roof which is still in reasonable condition.
I figured i'd first hit it with PVA sprayed on to give it something to stick to and keep dust to a minimum, then a tub of dulux weathersheild i've got sitting around. Not sure if i should go for normal PVA or waterproof, or this SBR stuff, so any advice would be appreciated

 

[misterhelpful]

@acepants

Just to let you know, you should always start a new thread rather than post your query in someone else's, but as you are a new member, and it is basically a query along the same lines, I'm sure the mods will let you off.
It does also give me a chance to expand a little further on my reply to @Tully, which may prove useful to them, as well as any future readers.

PVA will produce a film that water based paints will not adhere to. While they will generally cover the PVA, they will not be solidly bound to it and will flake off at some point, whether that be in a month's time or when you next try to paint over it is difficult to say as various substrates react differently. However, my advice for the underside of asbestos roofs, which are generally subject to condensation is to definitely steer clear of PVA. I wouldn't recommend SBR either as, to the best of my knowledge, it is just a bonding agent/additive for plaster and render and would probably produce similar results to PVA. They both are fine to use when plastering as they do bond to the plaster/render, but with a paint film there is nothing to really grip to.

For asbestos, the best paint primer I could recommend would be Zinsser Bullseye 1-2-3 Plus, as it provides excellent adhesion to the surface, and gives a solid base for almost any paint to bond to. There are obviously other brands and products out there, but being in the trade, I have always preferred Zinsser products, and it is generally the 'go to' brand for most decorators.
The link below contains a handy chart for their range of primers, and their best uses.

http://www.zinsseruk.com/wp-content/uploads/2012/05/Bulls-Eye-123-Plus.pdf

 

[acepants]

Thanks. Used Zinsser Bullseye 1-2-3, just about sprayed on ok through a 1.6mm conventional car paint gun without thinning - 2 coats of that and it looks great and really stuck on seriously well. Tempted to not even bother with the masonry paint now.