We have a guest post today by Owen Ingley of Plenitud Iniciativas, who has been experimenting with fibers in plaster.
“Greetings from Puerto Rico. I just wanted to give you a quick update on something that we’ve tried recently. The last emails we sent to each other I was asking you about fibers for plasters in the tropics. You confirmed my impression which was that any organic fiber will break down eventually in the humid tropics and potentially cause problems/issues with insects, etc. I told you that I had worked with chopped strands of fiberglass and that it had created some very strong plaster mixes, but we discontinued using it b/c of the health hazards.
Recently we started using chopped woven bags (the same ones we build with). We had made a sample with this as the fiber months ago and it came out great mixed in with our base plaster (clay, sand, lime, boric acid, and chopped bag fibers). The fibers seemed to make it much stronger (resistant to impact, picking at it, and spraying it with water). The only issue was that we didn’t have a good process for cutting it up.
Recently we discovered a technique that has helped a lot to speed up the process and we are now using this chopped bag in our base plasters for the whole project. We first chop up the bag with scissors (of course this could be mechanized) into small squares. Then we put a couple of handfuls of the material in a bucket with some water and use a drill with a paint-mixer bit to break it up into the individual strands. It only takes a moment to break it up with the drill. People could save all of their scraps during the project (we produce quite a bit of scraps when we build with the rolls) or designate some of the bag material to this process.
We’ve used this in our base coat mix and it even comes out just fine with the plaster sprayer that we are using.”