Structolite Basecoat Plaster
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Conservator



Joined: 29 Nov 2010
Posts: 24
Location: New Bedford, Massachusetts

PostPosted: Wed Dec 01, 2010 4:59 pm    Post subject: Structolite Basecoat Plaster Reply with quote

Structolite is a brand name for a product I've found invaluable in the repair and saving of plaster and lath walls and ceilings.

When I purchased my 1790s house in 1999, I found most all plaster surfaces intact under layer upon layer of later coverings. Pine panelling covering Homasote (aka Beaver board), simulated grained wood panelling, etc. all contributed to make the house as undesireable to all other prospective buyers as possible. (Kept the purchase price down nicely too)

The main reason I'm introducing this topic is to tell you of the success I've had repairing the split lath and plaster surfaces in my house. Most ceilings had had two additional ones attached over the decades. Fortunately the original lath and plaster remained (in various forms of disrepair) - with few exceptions - everywhere in the house. Since I find the undulation of the original plaster and lath a must, I was told of Structolite after I admired a friend's work on Martha's Vineyard. A "restored" house where blueboard or drywall is used with a skim coat is, in my view, a compromised restoration.

To repair loose areas of plaster in both floors and ceilings, I thoroughly removed the areas that were beyond repair, chamfered the edges to receive the new material, and used a spray bottle of water to saturate the old lath with water. Structolite is used as a base coat plaster and takes some getting used to if one has never used a plastering tool, trowel, or a hawk. My front parlor took a full year to restore but easily seventy-five percent of the original plaster is still there melded indistinguishably into the replaced Structolite areas with a rather thick ONE coat of the product. It takes overnight to dry. Come morning the Structolite infills are ready to receive the joint compound.

Apply simple joint compound and feather into existing plaster surfaces (leave it a bit high at edges where old meets new). Sand to flush and voilą. I've been able to save nearly all the plaster in this terrific old place with the use of this inexpensive product.

There's nothing quite as nice as seeing period woodwork against the irregular surface of a properly restored plaster and lath wall or ceiling. In fact I've rebuilt two period houses entirely with hand-applied lath, Structolite, and joint compound applied after the woodwork has been installed. Nothing compares.

So - I recommend the product highly to you purists out there. But please keep in mind it takes a bit of hands-on application to get the knack of it. Once you really "get it" it becomes highly enjoyable and its own art form. I'm interested to learn if anyone else has had the same kind of success I've had with this product.
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Jeremy Ballard



Joined: 22 Mar 2008
Posts: 127
Location: Providence, RI and Cape Cod, MA

PostPosted: Wed Dec 01, 2010 7:50 pm    Post subject: Reply with quote

Conservator,

I too have found Structolite a handy plaster repair product. I've repaired many rooms and ceilings with it. To add to your thoughts from my experiences:

Structolite needs to be moist to cure. A spray bottle as you mention works well for small areas, for larger areas I use a garden sprayer and in one instance a garden hose with a spritzer nozzle.

I would spray the substrate two or three times to make sure it had absorbed a good amount of moisture.

Whenever possible I would install the Structolite first thing in the morning. Structolite is moisture cure. Several times a day I will pop in and spray the repair. If you notice an area starting to look chalky you need to wet that area down more, it's moisture starved.

Structolite doesn't really like to be sanded. In large quantities it can be a little smelly.

Structolite can be installed in a variety of ways. One thick coat alone or with a skim of drywall mud. As a base coat for modern plaster topcoats.

You can also do a two coat Structolite finish. Install a scratch coat. The next day spray the repair several times. Mix up a Structolite slurry and install. As the day goes on keep checking on it. When the slurry coat starts to set you can spray it, then strike it smooth. Don't over work it or you will start to get bubbles. Before it fully sets you can knock any ridges off with a knife. You will have a smooth finish but will still have character.

I'm sure there are other variations but that's been my experience.

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Jeremy
Heritage Restoration, Inc.
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Conservator



Joined: 29 Nov 2010
Posts: 24
Location: New Bedford, Massachusetts

PostPosted: Wed Dec 01, 2010 9:58 pm    Post subject: Reply with quote

Jeremy Ballard,

Thanks. You've put forth the entire process. You're more thorough than I am I think. But we all have our way. And what works and stands the test of time is a pretty individual thing. I know several in our field who balk at its use. A Mr. MacKenzie from Brewster (not sure if he's still doing this work) put me on to it. The consistency of the Structolite to be used is key. I've found (through a good deal of trial and error) I'm able to apply a rather heavy one coat application (all the while spraying as you suggest so as to retard it curing too quickly) and get a sound finished product. Do you use joint compound to smooth and finish? I've often thought there must be a product out there that's less "slick" (for lack of a better word) but at the same time not making it look like those overstated "S" swirls so often seen on the walls of an American Italian Restaurant.

Do you always use the two coat method - using the first as a scratch coat?

I, as you, find this product a tremendous asset to saving original fabric.

Thanks for the input.
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Victor



Joined: 07 Aug 2010
Posts: 35
Location: Pacific North West

PostPosted: Wed Jul 03, 2013 1:40 pm    Post subject: Reply with quote

I too have used this product, in pretty much the same way as mentioned by Conservator.

One heavy coat, topped with a joint compound to blend into the existing.

What I've been wondering about the past few days is..

Should I have mixed sand with it? Should I have added a fiber to it? It seems so difficult to find concise information on how to do plaster repairs other than the company line of "just put some sheetrock in.."

Two years later the repair still looks good. It has a lot more solid thunk than the surrounding plaster work. Time will tell if I did it correct enough for it to last.
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Conservator



Joined: 29 Nov 2010
Posts: 24
Location: New Bedford, Massachusetts

PostPosted: Wed Jul 03, 2013 10:01 pm    Post subject: Reply with quote

Victor wrote:
I too have used this product, in pretty much the same way as mentioned by Conservator.

One heavy coat, topped with a joint compound to blend into the existing.

What I've been wondering about the past few days is..

Should I have mixed sand with it? Should I have added a fiber to it? It seems so difficult to find concise information on how to do plaster repairs other than the company line of "just put some sheetrock in.."

Two years later the repair still looks good. It has a lot more solid thunk than the surrounding plaster work. Time will tell if I did it correct enough for it to last.


Victor,

As lately as two weeks ago I used "our" tried and true recipe. In the house in which I live I restored the 18th ceiling in the best room this precise way. It' blends beautifully and stands up well (13 years). I see no reason to add anything to the mixture than is already in the product.
Structolite seems to work perfectly well on its own. One note: Any unused Stuctolite store in a very dry place. If improperly stored (like in a moist basement), it won't set up like it should.

Best of luck, Conservator
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johnleeke
Site Admin


Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Sat Aug 03, 2013 12:10 pm    Post subject: Reply with quote

Structolite already has an aggregate, perlite, which is a light-weight mineral. It does not need any additional aggregate.

Sometimes I have used Structolite as the base coat, and then made my own gauging coat out of gypsum plaster, lime paste and a very fine sand aggregate.

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John

by hammer and hand great works do stand
by pen and thought best words are wrought
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