New appreciation for Plasterers


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Old 04-16-07, 07:40 AM
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Thumbs up New appreciation for Plasterers

I mixed my first batch of plaster yesterday. In fact I still have it today. It set up in the pan before I could even get it out of the pan. I was really runny one minute and about two minutes later it was hard as a rock. I was using plaster of paris. My hat is off to anyone who spreads this stuff for a living. You must have some sort of secret, care to share????
 
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Old 04-16-07, 07:35 PM
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Secrets will cost you. Anti gravity spells: your first born. Formulas for plaster retarder: an arm and a leg. How to get in on the wall before it sets: last I checked the going rate is a new F-150 pickup.

You used the wrong material. There are many different kinds of plaster and different materials are used for different jobs. What are you trying to do? How large an area? How thick a coating?

Technically, all gypsum plaster except Keene's cement is plaster of Paris. But this is more than you want to know. Tell us what you are doing.
 
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Old 04-17-07, 06:29 AM
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Tightcoat knows how to do it right! ........... but you may be able to make repairs using drywall products which are more user [diy] friendly. It all depends on what you are trying to do.
 
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Old 04-17-07, 04:25 PM
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marksr: Drywall is only DIY friendly if you have studs to screw it on to. Mine are far and few in between. I've since been told this is a post and beam house. (like that meant it suddenly fixed the problem)
tightcoat: First born it is, she's all yours, warning she's spoiled to death.
Arm and a leg, well my arm is shot to hell, torn tendons, and I brusied the heck out of my leg, still want 'em?????
New F-150, whoa there fella!!!!
The holes vary in size, all fairly big, anywhere from 8"x14" to 20 some inches. With the studs being 28" apart that rules out drywall. I'd love to just screw a hunk to the wall and try to screen it over, but I'm afraid of what would happen to the wall if it took a really good rap. Did I mention I have kids??? My other problem is thickness. Nowhere is it the same. It runs from just barely there to almost 3/4" thick. I started out tightening up the loose sturdy part back to the wall using plaster washers. On a couple of walls I've been lucky enough to just be able to lay on some window screen and run some joint compound over it in coats. At the same time trying to get the walls somewhat flat. I threw a level on it the other day and some place dip in 1/2" or more. The plaster of paris is DAP brand. It's the only plaster I could find.
I did try to hire the job out, but he wanted my second born. (that's my boy and ain't nobody getting him )
 
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Old 04-17-07, 11:20 PM
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Now for plaster of the greater thickness you describe try to find some Structo-Lite or Gypsolite plaster. These are not necesarily the best but are pretty amateur friendly. All you do is add water except you might need to add a half gallon or so of sand to a 50# bag or a gallon to an 80# bag. A little raw gypsum will help it set or maybe a pint or so of your pofP in a bag. This is the base coat. Lay it down and flatten it with a long screed. For a finish I suggest some EasySand or somethink like it. There are better finishes but gain they aren't amateur friendly. The EasySand alone might be enough where it is just barely there.


BUT

You need something to hang that plaster on. What do you have? Wood lath? metal lath? Can you link us to a picture?
 
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Old 04-18-07, 06:25 AM
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It's wood lath. I haven't tried this link stuff on this forum, but see if this works. http://i118.photobucket.com/albums/o103/shopchallenged/Fixinghole.jpg
This is just a small sample of what I'm up against.
What is pofP? Will see if I can find some of that other stuff today. Do you buy online, or can you get this from a lumberyard?
 
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Old 04-18-07, 08:56 AM
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Picture is worth a lot. Here is what to do where the lath are exposed. First, wherever the lath cross a stud nail the lath. Screws are actually better in some ways. Screws don't jar more surrounding plaster loose but there is a risk of splitting the lath. If you have small enough screws try a few of those. The studs might be really hard.
Then paint the edges of the patches with a bonding agent. The best is Plaster-Weld by Larsens Products. There are other brands most of them look and smell like Elmer's glue. Let that dry. Mix up some Structo-Lite or Gyspolite to about the consistency of oatmeal. A little sand or set plaster or raw gypsum (land plaster or agricultural gypsum) will insure the plaster sets. Some plaster of Paris (pofP) in lieu of raw gyp might work as well. Now if you can't get Structo-Lite or Gypsolite I would be surprised if you can get gypsum plaster but if you can then mix it with plaster sand or masons' sand according to the ratios on the bag. Same consistency. Then in two passes fill the holes flush with the existing. The first pass press the material so some squeezes between the lath. This is what actually holds the plaster to the lath. Then fill it flush and screed it off even with the existing plaster. I like to screed it once with the straight edge horizontal and once almost vertically. If there are any low spots fill them in and do it again. Then with the edge of the trowel scrape all the residue off the surrounding plaster. Keep that edge clean. Now this is crucial. Very carefully with the edge of your trowel cut back the new plaster against the old plaster 1/16". 3/32" is ok. This is to allow room for your finish. When the plaster has set or the next day or later then finish it with EasySand or a setting type joint compound. This is not how I would do it but if you can't find plaster you almost certainly won't find gauging plaster or a prepared plaster finish so use the joint compound. It might take more than one coat. Keep the edges clean. Just as the EasySand sets you can mist it with water like from a spray bottle and slick it down almost as smooth as plaster. But if you don't get it god enough you can give it yet another coat and it can be sanded to elimiate the last trowel marks.

Another good idea in lieu of renailing the lath is to install some light gage (2.5) metal lath to the patch. Screw it where ever there is a stud and tie the edges where there aren't studs to the existing lath with wire ties. This greatly reinforces the patch. Then plaster as before. If the plaster in in the neighbor hood of half an inch thick you can use the metal lath. Waht you don't want to do is have lath sticking through the plaster. Now some here are going to tell you to square up the hole and put drywall in and patch the edges with joint tape and mud. I am telling you (sort of) how a plasterer would do it. Most of the secret is the right material. A good lumber yard might have what you are looking for. A mason supplier might and a plaster supplier if there is one around will. Patching plaster is NOT a good alternative nor is p of P. Molding plaster might work in a pinch but it is a last choice as it sets too fast, gets too hard, doesn't take to the addition of sand well and is more expensive.
 
 

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