Alabaster, Soapstone, Green and Lost Wood
Alabaster, Soapstone, Green, and Lost Wood
Outside of turning standard wood, you can use your turning skills using different types of wood and non-wood materials. Turning green would is a different experience, even from the same type of dry wood. Green will does not act or carve like dried wood and this can be a curse or the cause of some unique turnings. For the more adventuresome there a number of other wood and non-wood materials to explore.
A recurring question from both advanced and novice turners is how to turn green wood successfully into a bowl or wood sculpture. Turning green wood is an absolute pleasure, as the soft wet wood cuts very easily. Aside from dodging sap flinging off the lathe, the moisture in the wood also keeps the cutting tools cooler which translates to longer edge life, eliminates virtually all saw dust, and rarely exhibits any end-grain tear-out. Given all the benefits of turning green wood, what's the problem? Green wood shrinks. Green wood shrinks unevenly. As the wood seasons, the cells holding the moisture shrink. The shrinkage is greatest across the grain as compared to along the grain, with a difference as high as 15-25%. This uneven shrinking usually causes cracking and checks unless precautions are taken to prevent it.
The lure of turning green wood has been the cause of a great deal of frustration among novice and advanced wood turners. The potential rewards and possibilities are seemingly endless, and the appeal is so strong that it is tried and tried, again and again, with failure every time. The bowls always crack. This article is about how to turn green wood successfully. There are a few techniques that must be mastered, and a couple of tricks that need to be employed before the success rate makes it fun and worthwhile. These tricks and techniques do not require the use of special chemicals or preservatives, only a few good gouges, common sense, and perseverance. Hocus pocus is also not required, although incantations to the other side might add to the mystery of your success. Let us begin by explaining the reasons why turning green wood is so appealing.
Well not quite THE beginning, but a very long time ago, a great inland sea covered the area of land we now call Colorado. The creatures of that sea lived and died. Their calcium-rich shells collected on the sea floor for millions of years. The seas dried up, the Rocky Mountains pushed up through, and in some areas the heat and pressure changed the calcium deposits to alabaster. With saws, bulldozers, or explosives that alabaster is now extracted from the earth. Most of it is then sold for carving, but alabaster is also an ideal medium for lathe work. Unlike wood, alabaster has no grain structure, it cuts just as well in every direction. Unlike wood, it does not shrink and expand with humidity. Unlike some wood dust, alabaster dust is not known to be toxic. It is easy to work, easy to finish and just plain beautiful. So for us, the turners, in the beginning it's like this.
Items in smaller type are techniques or suppliers I don't currently use but either have used or believe to be reliable. What is it? Hydrated Calcium Sulfate (CaSO4•2H20) a crystalline form of Gypsum. Just about any saw that will cut wood will cut alabaster. The problem is the quartz crystals that are in the alabaster, they take the teeth off of anything.
I had the pleasure of watching a demonstration on the turning of Soapstone, needless to say, I found it interesting and decided to give it a try. I’ve turned a few pieces, a couple successfully, learned a few things, took some notes and pictures. Hopefully, this article will be of some use to somebody with less experience than I have, that is interested in turning Soapstone. The stone blocks I used are 3"x3"x5" and weigh 4.5 Lbs., not something you’ll want to eat for lunch, so wear a face shield when turning. Of course, dust isn’t good for you either, so wear your dust mask too! Soapstone is the softest of the stones and doesn’t respond favorably to conventional metal centers or chucks, it crumbles. The method I learned is to drill a hole in the top and use a wood dowel glued in and drilled, to mount on a screw chuck..The bottom is fitted to a wood glue block which will become the base. I turned a couple wood centers to use in the live center. Scraping tools seem to work better, a skew or gouge will work, but the trailing heel of the bevel will score the stone.
As this is written, I have just finished a piece for our next contest. The contest is to make a vase. There are two categories, under 8" and over 8". Since I was fortunate enough to win last year with my little 2" lidded pot, I thought I would try the process on a larger piece. To make an 8" vase with a nominal 4 1/2" diameter, I started with the configuration shown. The six pieces with the X's will be discarded after turning.
When wood is captured somewhere between the extremes of being completely sound and fully rotten, it can display magnificent beauty. The discoloration, prominent black lines and changes in texture that occur during the decaying process are known to woodworkers as spalting. Spalting is a by product of the rotting process that is carried out by a vast army of stain, mold and decay fungi. They are abundantly present in the air and soil, waiting for favorable conditions and a suitable host. Generally, wood moisture content of at least 25 percent, temperatures from about 40to 90?degrees F, air and food (especially abundant in sap wood) are what the fungi need. A tree or branch freshly fallen onto a damp forest floor in warm weather is asking for it.
Decay and rot is all around us. Fungus is everywhere and just awaits the opportunity to take advantage of the right conditions to grow and affect us in many ways. No, I'm not starting a great novel about the social and political conditions of our times, although that could be my next article if this one doesn't work out. What I am talking about is what happens to wood. Wood decays. Wood gets colored. One of the outstanding effects, sometimes, of this wood decay and coloration is what we call Spalt.