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Plaster for walls


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09-20-00, 07:16 AM   #1  
Where can I find plaster that can be used as a coating over drywall? We are repairing a large walkway in between two rooms and have drywalled the new studs and want to plaster over the whole wall, including the original plaster wall. Where might I find this type of plaster?

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Lisa

 
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09-21-00, 08:35 PM   #2  
Lisa_ohio:

"Plaster" on a plaster wall actually consists of a rough base coat with sand in it and a fine finish coat with lime in it. No one uses real lime based plaster anymore unless they're restoring an old house rather than just repairing it. All the repair compounds available for repairing plaster and drywall walls are gypsum based now, and that's what I'd suggest you use.

What I'd suggest you do is go out and buy some white carpenter's glue. Dilute that with water to get it thin enough to paint, and paint the surfaces you want the plaster to stick to with that dilute adhesive and allow it to dry overnight. Now apply one coat of any finishing plaster with a 1/4 inch "V" notched adhesive trowel and allow that to dry overnight. (The plaster will stick well to the dry adhesive on the wall.) Now, using the non-notched edge of that same trowel, fill in all the grooves with more plaster. In this way you can apply a 1/8 inch thick of plaster uniformly on the wall.

The first law of plastering is:

Joint filler = finishing plaster + glue

Which says that if you're having trouble sanding the plaster smooth, it's because you used joint filler instead of finishing plaster. The glue added makes the joint filler stick to drywall better, but it also makes it dry a lot harder and correspondingly harder to sand smooth.

Sand plaster smooth with sand paper if you're getting paid by the hour. Otherwise, use a hand sander with a 100 grit sanding SCREEN in it and a Scotchbrite scouring pad between the hand sander and the screen so the screen doesn't clog up. Hold the sander horizontally and tap it gently against the wall occasionally to allow the plaster dust to fall out of the scouring pad.

A bright light held close to the wall when you're sanding exagerates the roughness of the wall and highlights the areas that need sanding and those that don't. If you can get something that looks half decent with a light held close to the wall, it'll look professionally done under normal lighting.

Where can I find plaster that can be used as a coating over drywall? We are repairing a large walkway in between two rooms and have drywalled the new studs and want to plaster over the whole wall, including the original plaster wall. Where might I find this type of plaster?

Thanks,
Lisa
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09-21-00, 08:45 PM   #3  
Lisa:

When using ANY notched trowel, it's understood that you're supposed to hold it at approximately a 45 degree angle to the wall. So, a trowel with 1/4 inch "V" notches will result in a plaster thickness of approximately 3/16 inch. You can go to a thinner coat by using a 3/16" V notch trowel.

Also, if you've never plastered before, maybe stick with the pre-mixed stuff. However, if you decide to buy powder and mix it yourself, I like Synko Pro Set 90. It used to come in a yellow bag, but now it comes in a blue and white bag. Also, go to any place where the repair small appliances and ask for an old kitchen mixer blade, and use that in an electric drill to mix the plaster.

 
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09-22-00, 05:37 AM   #4  
Thanks for the reply. Where can I find finishing plaster? What exactly is it?
Lisa

 
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09-22-00, 09:53 PM   #5  
Lisa:

Not everyone uses the same terminology. The "finishing plaster" I buy says Synko Pro Set 90 Lite Sand on the bag. Home Depot sells it here in Winnipeg, but I've been using it for 13 years now, well before there was even a company called Home Depot. I call "finishing plaster" any gypsum based patching compound that doesn't have glue added that's mean to be sanded and painted. Other companies call it "topping compound", and Synko calls it a "drywall compound".

Synko is probably the biggest name in gypsum based compounds that are meant to be spread on walls. Their most popular line of repair compounds is the Pro Set line. They have Pro Set 30, Pro Set 60 and Pro Set 90. These compounds have a chemical cure that kicks in after 30, 60 and 90 minutes respectively. The plaster will still be wet, but it will be so stiff you can't mix it once that chemical set kicks in. You still mixthe powder in each bag with water though.

Pros like Pro Set 30 a lot because it hardens up quickly, allowing them to scrape it smooth with a taping knife and put another coat on. I use Pro Set 90 because it gives me a longer working time. I think Pro Set 90 comes in a premix tub, but I'm not sure of that.

Go to Home Depot and ask to see their gypsum based repair plasters. The most important thing is to make sure you don't buy a joint filler which is similar, but has glue added to it. I wish I had a nickle for every 17 year old in a home center selling joint filler to do repairs with. It's just fine to use joint filler for a small repair, like a screw hole, but you try sanding down a big patch of that stuff like you would have to do after a roof leak and you'll wear out your elbow.

If you're new to plastering, then you'd probably prefer the convenience of the premixed plasters. However, as time goes on, try to get away from these and go with the powder instead. The reason why is because if you use premix, you can't make it thicker and you probably don't have a mixer in an electric drill to make it thinner fast and easy. You're pretty well stuck with the plaster consistancy they sell you. However, with a bag of Pro Set 90 and a gallon of white carpenter's glue, I can mix a plaster that will be sticky as sap and hard as a rock when it dries or soft and easy to sand smooth, and anything in between. In general, you want the first coat to be hard and sticky so that it will stick well. You're not as concerned about sanding it because you'll be covering it with another coat anyway.

I don't know if I answered your questions. I would probably use Synko Pro Set 90 for your project. The only concern I have is that it's fairly soft and you may thing it's too soft when it's dry. However, in spite of it's softness, I've never had a problem with it in my apartment block over the course of the past 14 years.

 
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09-22-00, 10:03 PM   #6  
Lisa:

If your Home Depot doesn't sell Synko plasters, maybe don't buy whatever they sell.
Phone around to the drywall wholesalers in your town and ask specifically for Synko Pro Set 90, if they still have it in stock, or the new version called Pro Set 90 Lite Sand, which I'm told by the sales rep is exactly the same, only in a less colourful bag.

I'm sure Synko isn't the only company that can make a good patching plaster, but I KNOW Pro Set 90 is good because I've used different patching plasters, and I know it's easy to spread smooth and it's easy to sand smooth when it dries, so if you use this plaster, then if you don't do a good job it won't be because of the plaster. If you use a different plaster and you don't do a good job, the question is still open.


 
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