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Still, before building it would be a good idea to mix up some test samples, dry them and see if they burn. The most common test is to apply the flame of a propane torch to one spot on a block for a minute. If the formula contains enough nonflammable material, the block will glow red-hot where the flame hits, but it won't sustain combustion once the flame is removed.

BLOCKS OR FORMS OR ... COB?

Both blocks and slip forms have their advantages. With blocks, there is no lifting of slurry, which again, at 85% water, is very heavy. Instead, the slurry is dumped into block forms at ground level, where the blocks are left to dry (thus losing most of their weight). With slip forms, the slurry has to be handled only once, since it's poured directly onto the wall. But there is a lot of heavy lifting involved, and the wall won't start to dry out until the last load of slurry is dumped at the very top. Virginia started with blocks, but ran out and ended up using slip forms, while Andy used slip forms all the way. Both made their walls 12" thick.

If you plan on using slip forms, consider extending the window frames down to the ground, putting in some corner posts, and building a post-and-beam structure. That way, you can nail your forms onto the corner posts and window/door frames, which is a quick and convenient way to build. Also, the extra lumber will add strength to your building.

By the way, there is a third alternative: both papercrete and fidobe can be cobbed. To do this, you first dump the wet slurry onto a piece of shade cloth to drain. After several minutes, you can pick up the slurry, which will have become quite thick, with your hands (always wear rubber gloves when handling papercrete) and sculpt it to your heart's content. Cobbed fidobe we think offers the best of both worlds, giving you the free-form creativity of cob, but with the higher insulation value of fidobe. (For more on cob construction, see "From the Ground Up," November 1998, MEN #170.)

PUMPS

While many a builder has tried, no one has yet come up with a surefire method to pump slurry. We've heard lots of anecdotes, some of them conflicting. For example, one person we know used a diaphragm pump with great success, but another had a lot of trouble with a diaphragm pump that kept clogging. Others have had pumps work for awhile, then break down. Most pumps, even those designed to pump gravel, work best when pumping a substance with a high water content. But this goes against the principles of papercrete, which demands that the slurry be as dry as possible when applied to reduce subsequent shrinkage.

A number of people are looking into the pump situation - a grout pump is a likely candidate - and we plan to post regular updates on our Web site, www.papercretenews.com , as we find out more. Once pumping slurry becomes commonplace, it will revolutionize papercrete construction by eliminating a lot of the physical labor.

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