gluing plaster

[kirkendale]

I'm working on a building flat made of cast plaster wall sections. Behind the plaster panels will be a wood frame ( 1x3 frame and masonite). My question is should I seal the back of each panel before I glue them to the wood or not ? I have sealed the wood to prevent it from warping. I had thought to white glue each panel together end to end and use an adhesive like no more nails to glue them to the masonite backing. I want the adhesive to also act as a levelling agent. So should I seal the plaster ?
kj

 

[MasonJar]

I would not bother to seal the back of the plaster - the glue will work better on a porous surface than a non-porous. It will also take forever to dry if sandwiched between two non-porous surfaces (i.e. sealed masonite and sealed plaster).

If by "levelling" you mean "gap-filling", you might try something like latex caulking to keep the plaster flats in place. It is goopy (that's the scientific term, BTW ) enough to account for any uneven spots in the back of the plaster.

You might want to use something other than white glue to glue them together. The white glue will soften if you finish the plaster with water-based techniques after installation. It will also resist said finishes, or at least look different, and it is not carvable to hide any gaps. You might be better off using plaster to glue them together - just wet the castings on either side of the joint first.

Hope that helps.

Andrew

 

[kirkendale]

Andrew, thank you. :thumb:
I was not sure if the dry plaster would affect the adhesive... then again its not like it would pull the water out since there is no water...

I haven't looked into which "goopy" gap filler I will use, thats my next step. To help grip the panel back I was going to scrape a few narrow grooves into them.

I was thinking ( or not ) that using a bead of plaster to help join the panels would be too thick. My panels are of a 3 foot concrete pilaster on one end and 22' brick wall for the balance = 25' scale panel. I hope to reduce / eliminate any gaps between the panels by rubbing them together to wear them down to match with each other.

thanks
kj

 

[MasonJar]

Maybe you do not even need to glue them together at all. Cement them to the wood frame, and then use plaster only to hide the joint, rather than secure it. I agree that a good physical fit from sanding would go a long way to hiding the joint.

Andrew

 

[kirkendale]

Andrew, I did a test using some Mono Ultra Exterior white sealant that I had around. The plaster to plaster joint was good, I was able to pull it apart but it was a good steady pull. Then I gap filled the plaster to some masonite, I have not been able to pull it apart.

I'm now thinking of sticking the panels to each other, then as one unit placing it onto and sticking it to the masonite.
I plan to post a couple of pics soon.

kj

 

[MasonJar]

I would suggest that the caulking you use be latex, rather than silicon based. THis way if you get some where you don't want it, at least it can be painted.

Looking forward to pictures!

Andrew