I own an old house with beat up and cracked plaster walls. My father suggested I could renew the wall surfaces with a bonding agent and new basecoat plaster as a finish.
He suggests scraping the old loose stuff away, mesh taping the cracks and applying a bonding agent (I bought Deck-o-weld). Then troweling on the basecoat plaster thin and finishing in the traditional way with the ol’ green sponge with the handle on it…
He rec. the basecoat plaster to renew the finish because it’s wayy stronger and won’t crack as readily as finish coat.
The ol’ man’s pretty smart after 30 years as a painting contractor and says he’s done many a time before.
I’ll grant him that, but is this legit?
Can anybody suggest a better way to renew the walls.
What about matching the smoother finish better, rather than the random fan patterns the sponge will yield?
Any coaching here would be much appreciated.
Thanks,
pat
Replies
I'd been thinking about posting this for weeks and then did so without looking just down the line--plaster ceiling question is along the same lines.
So what about what my Dad thinks?
new sheetrock
Beer was created so carpenters wouldn't rule the world.
In my experience with base coats ( like Gypsolite) is, that unless you put it on thick enough, it does not have any strength. It is best when it is min 1/4-3/8" thick (min.). You can go over it with a veneer plaster,but you better be prepared to work quick, especially if your going to fine finish it flat. Also do not allow the bonding agent to dry before you apply the finish. If dry it can become the bond breaker. Some speciality bonding agents can be put on and allowed to dry (up to a day) and then become reactivated when the wet material in applied. Another option is to use synthetic stucco finish like STO or other EFIS finishes and apply them direct to the wall and rub out with a plastic trowel, allowing the thickness of the aggregate to determine the finish thickness. These products are often used outside but you would be surprised at how they stick and how easy they are to trowel flat. You can get it anywhere from fine sand to course aggregate or a few sizes mixed to get a finish call worm. They come premixed in 5 gal.and can be custom colored to provide a final finish.
I can't challenge your dad's success, but I don't think this is workable. The old first coat wasn't a finish plaster and will never look like it. Finish palster was made different for a reason. Also, like someone else said, I don't know that it's strong enough in a thin layer. You are going to be building up over the face of the wall with something that's going to be hard at best to sand, and your wall will show the irregularity.
Let us know how it looks when it's done - and how it holds up. Maybe we can all learn something.
Don K.
EJG Homes Renovations - New Construction - Rentals
This is what I thought aobut the basecoat too. I used it in one spot a few months ago and it's much much coarser for one.
"The old first coat wasn't a finish plaster and will never look like it..." Yeah. It's interesting though.. all the screeds are still in place around the doors when you pull the casings off, and I believe it is actually horsehair I see in it, apparently for reinforcement.
thank you,
Waters
Waters - You are probably correct, that you are seeing horsehair as a fiberous reinforcement. It was an old product - probably 1930's at the latest. As far as the basecoat being coarser, that it is. It is made with sand as a part of the mix and is often called the scratch coat. The idea is that you go over it with two more coats. The finish coat is plaster mixed with a slaked lime - no sand at all.
From the sound of the threads, you are heading towards using more modern materials, nothing wrong with that.
Good luck.
Don K.
EJG Homes Renovations - New Construction - Rentals
I've been working on such a project in my own 1830's home for a year. Anyone involved in this work may want to refer to the article in the June/July issue of Fine Home Building, "A New Way to Restore Old Plaster." Some of his techniques to finish with a smooth wall don't work for me (re-wetting the wall and then using a rubber grout tile). But it's a place to start. Using mesh tape and cloth is a good idea, although the wide widths are not easy to find. Here's a good supplier:
http://warehousebay.com/catalog/product_info.php?cPath=291&products_id=1620
I also haven't found the need to augment the compounds with sand. My first work has been up only a year, but it's looking good.
I have experimented with skimming the old plaster with just about every DW compound known to man, and I'm still learning, still trying to do it with as little sanding as possible. I am just experimenting with Structolite this week. At my low skill level, much sanding is required. However, I'm rather proud of my end product after the wall is primed and painted, even in "critical lighting situations." If you use the mesh, I would start with the setting compounds just to ensure a good adhesion. After that, any of the premixed stuff sticks just fine, and the wall will look like a smooth plaster wall, even if you use the softer sandable stuff. I don't like the textured plaster look in our federal style farm house, so painting with a roller with a short nap was important. You can't avoid a bit of texture unless you spray, I suppose, but I'm not set up for that.
I've just spent the last two days scraping off some old scaling skim coat, probably 100 years old, that was under the old wall paper. This is a time-consuming labor of love. I could never pay anyone to do this. Good luck to anyone undertaking this work. And thanks to all for your tips. Glad I can now pass on some of my own experiences.
Marc
Marc5 -
Noticed you said you don't want texture on the wall from the roller. I have a suggestion - try one of the foam rollers. Used them for the first time about a month ago and the finish is as smooth as can be. The only downside - the rollers are about 5-6" wide so it might take a little extra time. We were working on doors so it made no difference, actually was easier. The ones we used were thin too, maybe an inch or so thick.
If you can't find them, let me know and I'll dig one out of the painting box for more info.
Don K.
EJG Homes Renovations - New Construction - Rentals
Thanks, Don, for the foam roller idea. I have only seen the very narrow ones for trim, but I will do a search for some bigger ones. This will give me a new incentive to make my walls extra-smooth! Anyone else have a supplier?
Marc
There are many approaches to this problem. I'm in the middle of replastering such a a room as you describe. I would mesh tape all cracks, dig out any loose plaster & fill with a setting type spackle like Durabond 90. I would then skim coat the entire room with joint compound mixed with plaster of paris and water. If you haven't worked with this before, don't do it...it sets too fast and you really have to move. Instead, use a spackle mix called easy sand 45. This gives you enough time to skim and float the walls smooth, and it will sand afterwards.
Also you might want to look up "D Mix" here in the archives. It's used for this very type of thing and is similar to the plaster mix that I use, and works quite well. You have to have two people to do it though.
The Easy sand 45--that's just setting type joint compound, right?
Waters
Yes, it's called Easy Sand because you can sand it afterwards. The 45 indicates the working time you have with it if you mix according to the instructions. It is a setting type of wall spackle yes. The Durabond 90, which is also a setting compound, you really can't sand effectively as it sets too hard.
I think a better solution would be to use the fabric that covers the entire wall and is plastered over, or has been impregnated with plaster so you wet it and put it up like wallpaper. Less likely for cracks to happen again.
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69506.6 in reply to 69506.1
"I think a better solution would be to use the fabric that covers the entire wall and is plastered over, or has been impregnated with plaster so you wet it and put it up like wallpaper. Less likely for cracks to happen again."
This is probably the best solution of all.
Thanks all for the responses.
Ol' Red Hemlock would say, "Git busy and DO SOMETHING, even if it's WRONG!"
So I pulled off any loose plaster, taped cracks, rolled on undiluted deck-o-weld, troweled on finish plaster over it 1/8" and less while it was still tacky and finished it out with the sponge.
Remembered about halfway around the room that it's best to start at the ceiling with the sponge rather than try to 'cover your tracks' with it in the middle of the wall.
Texture is pretty aggressive in places, in the right light you can pick out the swirls and nicks, but what the hell! It's wayy better than looking at a bunch of cracks and bad patches from years previous. Somebody even put masking tape over the cracks and painted over that!
Thanks much for the info. Plenty of other rooms to try these other suggestions.
Waters
What's this fabric called and where do you get it?
Thanks,
Pat
I've used garden fabric and glued it on with Plasterweld, or Thorobond type bonding agent, then skimmed from there. But there is a fiberglass mesh made in 3' wide rolls that you can get. A good mason supply should carry it, or a good independent lumber yard.
http://www.larsenproducts.com/plasterweld.htm
http://jimshare.com/ For fiber mesh
tear it all off my man, do yourself a dusty favor
I hear you!
I will remove the plaster entirely in a couple rooms, and use the techniques I've just learned of here to finish the rest.
Got to keep my marriage intact!
Removed the plaster in one bumpout wall to reframe for windows and woodstove installation and found some the largest old paperwasp nests I've ever seen! Old and yellowed.
Thanks all,
Pat