Rub R Slate Lessons

Rub-R-Slate mix- from a series of Lessons A low cost, “green” building formula created by Jack Bays in the 1920’s. Basic Asphalt Emulsion Information-for Rub-R-Slate use. In the 1920s Jack Bays developed a material he called Rub-R-Slate, which he used as a cushion flooring for factory workers. The information here is based on his basic formulas of clay, shredded cardboard and AE. I substitute shredded office paper and a commercial newspaper cellulose blown insulation product, (Cocoon brand) and/or sawdust. I like the sawdust best, and it is free and easily available where I live, in Northern California. Fine chopped straw, dry chopped shrubs can also be used, in fact, any dry organic, even seaweed, and grasses can be used. This is extra information that may help you with your experiments with papercrete and earthen floors or stabilized wall plasters. Asphalt Emulsion (AE) is a pudding-like additive to adobe and clay that will help waterproof it and stabilize the material. Is is available in 1-5 gallon cans, and drums, in a building supply store. Common brands are Henry 107, Black Jack, and Fortress to name three. Look in the roofing materials department, or in cellar and basement products area, where water proofing products are sold. Modern AE is a non-toxic, non off-gassing, tar-like substance, mixed with bentonite clay and water in stable suspension. AE is used for roofing and road/driveway coating. When added in small percentage to clay (5%-30%) it keeps clay from dissolving in rain or water. It is an ideal material for use in plasters placed around windows and doors for moisture protection/water intrusion. You can PAINT and plaster over an AE mix too. Using AE is not new, in the SW states it has been used for adobe houses for centuries, and “bitumen” has been used all over the world, especially the Middle East to protect clay bricks. It is painted on the base of buildings or added to adobes. I have made several varieties of mixes and I like the clay-Redwood sawdust-Asphalt Emulsion-sand mix the best for a very smooth plaster, and for flooring. Asphalt Emulsion has a “road tar” smell upon opening the can, but this dissipates in the mix and is not present when dry. Visit the website for the AE Mfg. Assoc.: http://www.aema.org/ for more information. Wipe down drips of excess with a wet cloth before it dries on your skin, tools, bowls. AE sticks tenaciously! but you can keep a bucket of water near and dunk tools, gloves, mixer blades in to keep AE from setting up.

Keep the can lid on as AE evaporates in open air. Brand names I have used are: Henry 107, and Black Jack. Other brands can be found in hardware & DIY stores. Mix using same size bowls, cans, or buckets for volume measuring, add the AE last, or right before you plan to use it. Use clean water, paper, and clay with no leaves, twigs etc. to avoid harboring bacteria. Soft clay is simply clay sitting in water for a period of time to become soft, by lifting it out of the bucket with a kitchen colander or strainer you are getting clay and water in the right weight for experimenting. Apply the mix thinly onto cardboard, heavy paper, canvas to make test mixes. Filling a deep pan or other form takes far too long for the mix to dry, and there is shrinkage. Jack Bays recommended thin coats applied over each other to build up floors, etc. I have found this material is almost waterproof, I placed thin “RRS cookies” in water for 24 hours, and when broken open the insides were dry. This may make it an ideal plaster for absorbent materials like straw bales, papercrete, unstabilized adobes, etc. Conversely a thick coating over every surface inch may also mean no breathing of the surface wall either. This could be a problem for trapped moisture in organic materials. Mixing AE and clay with a variety of materials such as sawdust, cross-shredded paper, cellulose insulation, and adding sand makes a very nice mix that trowels easily, and is a pleasure to work with. Like papercrete materials this mix can also have cement in it Try adding AE to papercrete formulas after draining the water out (basic papercrete is a very wet mix that sheds excess water. Pre-drain, then try mixing AE in. Sand is recommended in making stabilized clay-adobes when using AE, in traditional use. Don’t make samples unless the weather is dry. The best companion book for these formulas is Earth Brick Construction by Hubbell, #2025--$16.00, extensive AE information: mixing, testing, use is given. Essentially Rub-R-Slate and its other formula names are a highly stabilized papercrete mix. Heavy weight building paper-tar paper- is asphalt embedded. It might be possible to use this as a substrate to apply Rub-R-Slate mixes. ( I use heavy cardboard, or recycled pressed paper display boards.) Many modern products did not exist in Bay’s time, so combine the best of both his recipes and new resources. Please let me know of your success and application use of these formulas. Caveat: Proceed with caution in mixing/building as with any materials and use common sense. Wear gloves and goggles, have a water source nearby, and work in a well vented area. Charmaine Taylor and Taylor Publishing are not responsible for problems with use/application of these materials.

** A CD “NUWAY Building Book” on CD Order code #8399- $19. is available from www.dirtcheapbuilder.com and offers the book Jack Bays wrote in the 1970s with 77+ pages of use history, case studies, experiements, formulas. Cool names like : "Liquid Marble, MarbleWood, Insuldown, Insulrock, Lithocrete, Hornite, and Terralithic" are variations in recipe contents. All pages plus two scans of Rub-R-Slate Lesson are included (from two typed texts, one is more readable than the other.)