Unibond Outside?

[cjgarlick]

Morning all -

Does anyone know if Unibond or PVA is sufficiently 'weatherproof' to be used as a sealant for a newly sandblasted (and therefore de-glazed) exterior brick wall? I would guess at about a 4:1 mix with water.... ?

Thanks in advance.

 

[Ant]

I presume you are looking to waterproof the wall - in which case I wouldn't have thought it would work very well - something made for brick like Thomsons Waterseal or similar would be better and much easier to apply.

 

[cjgarlick]

Thanks for the reply Ant -

Intention is not really to waterproof the wall, more to change its appearance.

Sandblasting has taken off the bricks' surface, leaving them textured like weathered sandstone, and has made them a uniform 'new' orange colour.

By 'sealing' the brickwork I want to add a very slight glaze, as the original bricks would have had, and also to try to darken them slightly and bring out some degree of tonal variation in the bricks.

I've done something similar indoors on a chimney breast, sealed with Unibond, and it looks great. My worry is whether it is weatherproof enough (rain, UV etc) for exterior application. I have used Thompsons waterseal in the past, which I agree is good stuff but doesn't really give the desired effect.

 

[masona]

I was wondering if you can put Unibond on first then Thompsons waterseal afterward ? Best to ring the manufacter product helpline

 

[cjgarlick]

That's a good idea. Are you saying you think Unibond alone will suffer ?

 

[masona]

Not sure,that why I say ring the helpline for advice. My opinion would be that I don't think it will stand up to the rain etc as the Unibond probably wash off as its mixes with water and need protection with a sealer (not sure what reaction with the 2 product) Why not Unibond the walls and see what happen as you got nothing to lose.

 

[cjgarlick]

Hello -

I'm reluctant to just go ahead, since we're talking about all four exterior walls of a very large house........ lots of work if it washes off in a few months. Could do a trial patch of course but hard to simulate (eg) a year's rain... and ideally I want this to last a lot longer than that. My main concern (which I think you're reinforcing) is that the stuff is nominally water soluble. As you say, I'll ring the manufacturer.

Thanks for all comments and help.

 

[Drew]

Unibond, is basically PVA glue, it is not suitable for exterior use, if you want something to enhance the apearance of the stone/brick try something like sealocrete's "all in one sealer" designed for sealing and enhancing exterior stone/work such as block paviors, flags etc but I can't see any reason why you can't use it on a wall.
Just been on the website, can't find any info on it, but you could email them and ask... http://www.sealocrete.co.uk/

 

[cjgarlick]

Thanks Drew - I'll check that out.