Camping and woodcraft - Scoutmastercg.com

70 CAMPING AND WCODCRAF'ithread is itself repellant of water, but the intersticesare leftopen.In the first instance it is not practicable to treatthe cloth before making it up ; the whole tent shouldbe soaked in a waterproofing mixture, or the " wax "ironed in, thus insuring that the seams are tight.Paraffine is used either plain (in which case it iuliable to crack or flake in cold weather) or combinedwith some elastic substance. The " mineral wax "callea ozocerite or cerasine (often used as a substitutefor beeswax, and sold by dealers in crude drugs)is not so brittle as paraffine, adheres better, and, likeparaffine, has no deleterious action on cloth, beingchemically neutral. I have not known of it beingused by tent-makers, but believe they should try it.Crude ozocerite is nearly black; when refined it isof a yellow color (cerasine) and resembles beeswaxbut is not so sticky. It makes a tough compoundwith rubber.The plain wax process renders cloth quite waterproof,but adds considerable weight, makes the stuffrather stiff, and increases its liability to catch afire,when exposed close to a stove or camp-fire.Cloth of class B is subdivided in two groups:( 1) Cravenetted goods, like duxbak and gabar-^,dine, are processed in the yarn, or by chemical treatmentapplied to the raw strands themselves beforethey are twisted into thread. Such cloth is not sowaterproof as waxed or oiled stuff, yet tents madeof it can be depended upon to shed rain. It is aspliable as plain cloth, not perceptibly heavier, and isnot affected by changes of temperature.(2) Willesden canvas (or twill, etc., as the casemay be), also known in England as "green rotproof,"is cotton stuff soaked in an ammoniacal solutionof copper that dissolves enough cellulose in thecloth to coat each fiber with a more or less impermeable" skin " of its own substance, and turns the materiala light shade of green. It is not so waterproof^s waxed cloth, yet sheds rain very well if the mate-