I Got So Plastered
As you can see by the above photograph, there’s a bunch of gray matter stuck to the wall on the left—that’s PEP (Paper Enhanced Plaster). The color is a dark gray at the moment, but once the walls dry out (pick a year), the color will almost be white.
I first covered the wall studs with some leftover 6 mil plastic that I previously used as a drop cloth. I did this to prevent moisture from wicking into the 2″ x 4″ wood framing.
Once the plastic was up, next came metal lath. Metal lath comes in 27″ x 96″ and has a diamond shaped netting that holds the plaster in place. Traditionally, plaster is applied in three coats: scratch, brown and finish. The idea is to gradually build up the surface of the wall, leveling out the valleys and hills as you progress. Since this is not a traditional house, I decided to break tradition and put on all three coats at once. I can’t imagine doing this with regular plaster—it just wouldn’t adhere to the lath. But, by adding slurried paper to the mix, it’s sticky enough that it holds without too much trouble.
My first mixes had some problems though. I found that the slurried paper that I was using contained some chunks of office paper and ads. This is okay for cordwood work, but just causes all sorts of problems for plaster. I put that slurry to the side and made some fresh slurry using nothing but 100% newspaper—it went on like butter and the whole wall (8′ x 11′) only took six batches of mortar. By comparison, a cordwood wall (8′ x 8′) takes about 24 to 25 batches. The finished product is about 1/2″ thick.
Now granted, the look of the wall is definitely textured. If your looking for a perfectly flat wall, then this isn’t for you, but if you’re looking for a imperfect, handmade finish, this might be worth a try.
My standard disclaimer applies here: This product is untested, it may explode into a maze of cracks, so don’t try this at home (yet). Over the next month or so, I’ll have a better idea how well it works and I’ll be sure to share the results along with a few photographs.
Natural Plasters
Since we’re on the subject of plaster, I’ve just finished reading a new book on the subject from New Society Publishers: The Natural Plaster Book written by Cedar Rose Guelberth and Dan Chiras. The book highlights natural plasters used with strawbale homes, but there’s plenty of good information that can be used for anyone interested in natural plasters for any style house.
Natural plaster is preferred over cement stucco for strawbale homes. According to the book, cement stucco leads to nothing but problems when applied to strawbale walls. It doesn’t breath like natural clay plasters and can lead to trapping moisture inside of the walls. It also wicks moisture too.
These samples are still quite wet and it will at least be a couple of weeks before any meaningful results can be obtained from these earthen plasters.
I still have a problem though with using clay for exterior walls here in the Midwest. For the arid southwest, it might be acceptable, but for around here I’m skeptical. The book states that linseed oil can be added to the mix to make the walls more durable.
I will agree though that portland cement and/or hydrated lime require lots of energy to produce. I think about that quite often when I’m mixing up a batch of mortar. Maybe natural plaster could be used for the interior walls of the house? With that in mind, I made some sample mixes this week using clay from the hill in back of the house.
The clay has quite a bit of silt mixed in with it, so I’ll be curious to see how the samples turn out. I tried various combinations of paper, clay, sand and hydrated lime. I still have visions of the commercial that Saturday Night Live did back in the 80’s. It was a commercial for a car made out of clay. “Hey hey, it’s Adobe… the little imported car that’s made out of clay for $179.00” The commercial featured a couple dressed in white tennis outfits getting out of the car. As you can imagine, their clothes were a bit discolored from sitting in a clay car. Hopefully, the samples won’t rub off like that.
Somewhere Under the Rainbow