Pedestrian and cycle campers sometimes go in for the utmost possible lightness and compactness of outfit that will serve their purposes. For tents they use the most finely woven cotton, linen, or silk, not waterproofed, but depending upon extreme closeness of texture to shed rain. The cloth may "spray" a little in the first heavy downpour, but it will not leak so long as nothing rubs it from within.
I have a sample of very close-woven silky cotton stuff from which a Puget Sound tent-maker turns out "A" tents complete of the following weights: 3 1/2x7x4 ft. high, 2 lbs.; 4 1/2x7 1/2x5 ft., 2 3/4 lbs.; 7 1/2 x 7 1/2 x 7 ft., 5 lbs.
Lightest of all rain-proof materials, strongest for its weight and, of course, most expensive, is silk. It can be woven more closely than any other textile and so needs no waterproofing (oiled silk, such as surgeons use, weighs more than "balloon silk"). Genuine silk is the toughest of all fibers; but it does not stand much friction, hence should be reinforced at all friction surfaces, and rolled up when packed away, not folded in creases. It is unsuitable for any but special tents made for pedestrians. A London maker, T. H. Holding, sells a tentlette (if I may coin a term) of Japanese silk, in wedge shape, 6 x 5 x 4 ft. 6 in. high, that weighs under 12 ounces; and it is a practical little affair of its kind. Of one of these he reports: "It has stood some of the heaviest rains, in fact records for thirty hours at a stretch, without letting in wet, and I say this of an 11-oz. silk one".
If one has home facilities, there is no reason why he should not make a good job of waterproofing for himself.
The cheapest, simplest, and, in some respects, the most satisfactory way is to get a cake or two of paraffine or cerasine, lay the tent on a table rub the outer side with the wax until it has a good coat-ing evenly distributed, then iron the cloth with a medium-hot flatiron, which melts the wax and runs it into every pore of the cloth. The more closely woven the cloth, the less wax and less total weight.
Some prefer to treat the tent with a solution of paraffine. In this case, cut the wax into shavings so it will dissolve readily. Put 2 lbs. of the wax in 2 gallons of turpentine (for 7x9 tent or thereabouts). Place the vessel in a tub of hot water until solution is completed. Meantime set up the tent true and taut. Then paint it with the hot solution, working rapidly, and using a stiff brush. Do this on a sunny morning and let tent stand until quite dry. The turpentine adds a certain elasticity to the wax; benzine does not.
For tents to be used in cold weather before an open fire; the following process is better:
First soak the tent overnight in water to rid it of sizing, and hang up to dry. Then get enough soft water to make the solutions (rainwater is best; some city waters will do, others are too hard). Have two tubs or wash-boilers big enough for the purpose. In one, dissolve alum in hot soft water, in the proportion of 1/4 lb. to the gallon. In the other, with the same amount of hot water, dissolve sugar of lead (lead acetate — a poison) in the same proportion. Let the solutions stand until clear; then add the sugar of lead solution to the alum liquor. Let stand about four hours, or until all the lead sulphate has precipitated. Then pour off the clear liquor from the dregs into the other tub, thoroughly work the tent in it with the hands until every part is quite penetrated, and let soak overnight. In the morning, rinse well, stretch, and hang up to dry.
A closely woven cloth should be used.
This treatment fixes acetate of alumina in the fibers of the cloth. The final rinsing is to cleanse the fabric from the useless white powder of sulphate of lead that is deposited on it. Failures are usually due to using hard water, or a less proportion of alum than here recommended, or to not dissolving the chemicals separately and decanting off the clear liquor. When directions are followed, the cloth will be rain-proof and practically spark-proof, but not damp-proof if you use it as a ground-sheet to lie on, or if exposed to friction. After a good deal of use, the tent will need treating over again, as the mineral deposit gradually washes out.
Remember that cotton goods shrink considerably when first soaked.
Shave up about a pound of laundry soap and dissolve it in 2 gallons of hot water. Soak the cloth in it, dry out thoroughly, and then soak in an alum solution as above, and dry again.
I have had no success with the alum and lime method mentioned by " Nessmuk".
Good waterproofing compounds can be purchased teady-made from some tent-makers.
The following recipes, although not suitable for tents, are useful for other articles of equipment, and are included here while on the subject of waterproofing cloth:
For ground-sheets to use under bedding: get some of the best grade of boiled linseed oil of a reputable paint dealer. One quart will cover five or six square yards of heavy sheeting. Pour it into a pan big enough to dip your hand into. Lay out the cloth and rub the oil into it between your palms, using just enough oil at a time to soak the cloth through, filling the pores, but leaving no surplus. Then stretch it in a barn or garret, or other dry shady place, for one week. Finish drying by hanging in the sunlight three or four days, fi.st one side up, then the other.
A flexible enamel such as is used on fly lines for fishing is also useful for finishing seams in articles sewed up from waterproofed cloth.
Get some old photographic films, soak them in hot water, and scrub off the gelatine surface with a small stiff brush.
When they are dry, gradually add them to acetone until the solution is of the consistency of varnish. If a drop of it dries transparent and firm, it is fit. In this state it makes a strong cement or hard rod varnish that will not crack or peel. To make it flexible, proceed as fol lows:
Add common benzine to the amount of one-fourth the acetone. Shake well. Let the mixture stand and settle. Draw off the clear varnish from the water at the bottom, and test as before. If it does not dry clear and firm, add a little more benzine.
Now add castor oil to the amount of two-thirds the weight of the dry celluloid films that have been used, shake well, and give it time to thoroughly mix. Test: if not tough enough, add a little more oil. If too soft, add a little celluloid solution.
This does not evaporate so fast as a solution of celluloid in amyl acetate ("banana oil"). The castor oil gives it its flexibility.
Use Diamond dye of a kind recommended by the makers for cotton goods. Follow directions on package. Dye the tent a deeper shade than what you want in service, for it will fade considerably in sun and rain. The dyeing must be done before waterproofing.
In a tent of thin material it is important that the widths be narrow, to keep the shelter taut when set up, and that the seams be reinforced with tape, to relieve the cloth itself from overstrain. Eaves, bottom, and corners should be strengthened with double cloth.
If there is a ridge, have it reinforced, with tapes attached whereby to suspend the tent from an outside ridge pole when desired.
There should be a sod-cloth all around, unless the tent has a sewed-in floor.
A tent that is to be used in " fly time " is certainly incomplete without a curtain of cheesecloth or bobbinet to exclude insects. This is best made to attach or detach at will, if the tent is also to be used iate in the season with an all-night fire in front of it.
All tents that are made to close up at night or in bad weather should be fitted with screened windows for ventilation. The smaller the tent, the greater the need of this.
Guy-rope slides, if there are any, should be or galvanized wire. Grommets (galvanized iron rings worked in by hand) are much better than brass eyelets which are likely to pull out.
Ropes and beckets are to be small but strong; braided sash cord is best for a ridge rope.
Tent pins of steel are more durable and less cumbersome than wooden ones. In well forested countries none need be carried, but four steel corner pins help in setting up the tent quickly.