Alum, Larsen's, plastering over surfaces

I've read posts about alum, which people say you can apply to wallboard so that plaster will adhere. This would be in lieu of using blueboard. All the supplier's I've called haven't heard of alum. Where can I get it? Is it a powder, you mix with water?
I've also heard of Larsen's Plaster-Weld, for plaster adherence. It's not cheap, however. A local supplier has it:
1 gal. $23 5 gal. $105
I have no information on it, but would guess that a gallon would cover 250 square feet. I'm thinking of this for plastering certain non-wallboard surfaces, either finish coats or two-coat.
TIA for any info.
Dan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
are we talking about Plaster = sand, lime, ect or Drywall compuond? If you are talking about real plaster why not just use drywall compound? you can get pretty much the same visual effects as plaster if applied correctly....the walls in my home are plaster and button board with about 15 years of paint on top of them I wanted to recreate the plaster look and did so with drywall compound you wold be hard pressed to tell the difference.. Dan_Musicant wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:
:are we talking about Plaster = sand, lime, ect or Drywall compuond? If :you are talking about real plaster why not just use drywall compound? :you can get pretty much the same visual effects as plaster if applied :correctly....the walls in my home are plaster and button board with :about 15 years of paint on top of them I wanted to recreate the plaster :look and did so with drywall compound you wold be hard pressed to tell :the difference..
It may look the same, and I'm not speaking from experience here but I've been doing a fair amount of research, but drywall compound has some significant downsides compared to plaster. You can't build it up too much on a per-coat basis, you have to let it dry between coats and you have to sand between coats and you get a lot of dust. Plaster you can work much faster and be done with everything but the cure dry phase in a matter of minutes. I think that plaster's probably a whole lot tougher, as well. Also, if you are applying directly over lath, it's either plaster or work out some kind of intermediary layer, such as wallboard cut to size - either blueboard or wallboard treated with alum or another adherence layer, such as Larsen's Plaster-Weld.
Dan
:Dan_Musicant wrote: :> I've read posts about alum, which people say you can apply to wallboard :> so that plaster will adhere. This would be in lieu of using blueboard. :> All the supplier's I've called haven't heard of alum. Where can I get :> it? Is it a powder, you mix with water?:> :> I've also heard of Larsen's Plaster-Weld, for plaster adherence. It's :> not cheap, however. A local supplier has it::> :> 1 gal. $23 :> 5 gal. $105:> :> I have no information on it, but would guess that a gallon would cover :> 250 square feet. I'm thinking of this for plastering certain :> non-wallboard surfaces, either finish coats or two-coat. :> :> TIA for any info. :> :> Dan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.