Questions and Comments From the Field
This first letter comes from the U.K., and I want to congratulate him, as he is this month's winner of the Plaster Man/Walls & Ceilings T-shirt. Here are the letters:
Hawk downHello Plaster Man,
Could you tell me what the difference is between aluminum and magnesium hawks? What are their performance differences and which works better with plaster?
Both types of hawks are fine for plastering. Some prefer magnesium because it is a higher grade metal and therefore is more durable. They also say it's lighter in weight. Plaster is heavy enough, so any help in lightening the load is always welcomed. I hope that helps, and I wish you success.
I would like your opinion on my approach to a project. I am resurfacing gypsum board walls with a splatter orange peel texture, and ceilings with popcorn, all coated with old flat paint. My goal is a polished, smooth troweled surface. The ceiling I would wet and scrape down (I am concerned about its ability to hold the weight of a coat of plaster), use a bonding agent, scratch in and plaster with one coat of my finish material.
The walls I would use bonder and plaster with basecoat with Perlite plaster added (I would not add a lot of weight to nailed drywall and would float over orange peel easily). Then I would finish coat with autoclave lime and gauging plaster. What do you think? I want maximum working time and a polished surface, so it must withstand some hard water toweling. Can you recommend a good felt brush for water toweling?
I would say your approach to this project sounds pretty good. I would only suggest that you make sure that if any cracks are visible on the surfaces, you embed mesh into your basecoat, just to ensure they don't come back. It's frustrating to finish out a wall or ceiling, only to have cracks appear through the new surface you've spent so much time and money on.
Also, I wouldn't be too concerned about the ceilings ability to hold plaster. If you were re-hanging over the old, now you've got some serious weight you're putting up on the ceiling. The thin coat of plaster you're adding will have little effect weight wise. Still, I like to check the stability of the old board and if there is any movement in any of it, adding a few screws helps quite a bit to firm it up. If you're not going to use a pre-mixed finish, then lime and gauging is a good way to go for the smooth. There's a lot more toweling required but the finish is extremely hard and durable. It will also give you the longest working time-about 11⁄2 hours from start to finish.
As for a felt brush, there are many on the market. Thanks again for writing and I hope this project works out well for you!
Rusted toolsHi Robin,
I have a few trowels but they seem to discolor and have a build up on the trowel. What is the best method to clean my trowels to keep them looking good?
If you use a stainless steel trowel, you won't run into the discoloring problem. Some trowels have a problem with discoloring and rusting. As a tip to care for your trowels: scrape them clean with a margin trowel after using them. Scrub any other material off with brush and water and then use WD-40 as a coating on the metal areas. This keeps them in great shape and helps with the build up of plaster that can occur on them. We also find WD-40 helpful as a film on the inside of 5-gallon buckets and barrels just before mixing. It doesn't affect the mix, and helps make clean up a lot easier, especially when basecoat gets wild and sets up before you can get it out of the bucket.
I wanted to compliment you on your recent article on Venetian plasters and the repair of the decorative ceiling. I think it was one of your most interesting.
There was one small technical mistake you may want to be aware of. You referred to the rubber mold that you painted over the model as being called the "mother mold." The term "mother mold" generally refers to the hardened case, which supports the rubber mold (like a mother holding her baby). Of course, the case, or "mother mold" can be made of plaster, fiberglass, resin or any other strong supportive material that will hold the rubber in place to keep its shape.
If you have the opportunity, I highly recommend taking the two-day mold-making course offered by PolyTech, in Pennsylvania. I had been making molds and casting for many years but this enjoyable course really helped broaden my understanding of the available materials and techniques in this segment of the industry.
I was the only plasterer in my particular class. The rest of the students consisted of sculptors, who wanted to learn how to reproduce their works of art and to an FBI agent, who wanted to learn how to make copies of household items so they could be used to conceal surveillance equipment. This class was a lot of fun, and I learned a lot! In fact, I was so impressed that I paid to have one of their technicians do a half-day workshop for my entire staff of plasterers and cement masons at our seminar last year. But if you can go to their facility and see the full range of products and equipment, it's much, much more informative.
OPCMIA Job Corps
As a further note on the ornamental plastering article that Rogers referred to: I was recently in Burlington, Iowa, and got a chance to talk to a fourth generation plasterer, Kenny Ita. We were talking about ornamental plastering. One challenge when making castings is being able to have them sit "flat" on the surface you're attaching them to. Sometimes, when making them the rubber mold inside the "mother mold" is not perfectly flat. It's tough to sand down the piece, and many times it's impossible to fill in the areas because it would throw off the even appearance you're trying to achieve in setting the pieces. Kenny had a great suggestion:
Whenever I run into this problem, I simply take the cast piece and place it on a flat table. I then take a wet towel and place it on top of the cast piece. Even though the piece is hard, the water moistens it and it will slowly flatten the entire piece. You can then attach it and it will be perfectly flat!
To close, I received a letter that I wanted to include here and then comment on next month. It's a topic that I think needs to be addressed, as it has a lot to do with attitude and the view of the plastering trade.
Just thought I'd drop you a line about some e-mails that have been going around about your last W&C article. It's even got me wondering. The magazine is read by tradesmen, not do-it-yourselfers. This is how we make a living. Teaching drywallers, painters, etc., to plaster to enhance their business is one thing. Teaching homeowners to do it themselves belongs in This Old House magazine. Tradesmen think you should be telling the homeowner to hire a plasterer. There ain't no pot of gold if there ain't no work. I hope you take this letter in the context it was meant, with all respect to you and your future.
To enter the T-shirt giveaway, send an e-mail with your name or your company name. My e-mail is firstname.lastname@example.org or you can send your entry and any letters to this magazine. Until then, Plaster On!