CANVAS INFORMATION

Cotton canvas, artists canvas, cotton/polyester canvas, polyester canvas, acrylic canvas, pvc canvas. loom-state canvas, waterproof canvas, etc; all are canvases in their own right.

The information below relates to cotton and cotton/polyester waterproofed canvas:-

•Cotton was the traditional fabric for canvas for many years and provided the benefits of high breathability and its ability to seal and become water tight. Stitch holes in cotton canvas will seal when the cotton gets wet and shrinks. Cotton fabric can be treated to ‘reproof’ if the water proofing has deteriorated. The disadvantages of pure cotton canvas is it is fairly weak in comparison to some other fabrics (which means pure cotton annexes and tents are generally very thick and heavy to compensate for this weakness), and that the fabric shrinks quite dramatically overall.
•Polyester fabric has the benefits of high strength (which means tents, annexes, tarps, covers etc can be lighter than pure cotton), and the fabric will not shrink overall. The disadvantages of polyester is that it cannot ‘breath’ (which means condensation will form), and it will not shrink around stitch holes which means water moves freely through these holes unless sealed with a seam tape or similar. Polyester generally uses a brush-on treatment for water-proofing (which can flake off when folded, damaged or worn). Polyester fabric cannot be DIY treated to ‘reproof’ it once the original ‘proofing’ has deteriorated.
•Modern good quality canvas is made from a blend of both cotton and polyester to get the benefits of both. The yarn or thread used to weave these canvas fabrics consists of naturally short cotton fibres which have been ‘blended’ together with short lengths of polyester then spun together as a continious thread or yarn. (Polyester filament is produced in a continuous length which is then chopped into short lengths before the blend process). The modern good quality external canvas provides good water repellant/proof properties, good wear and strength properties, is treated to resist both UV and mould, and has a long lasting color dye that is not only a good surface color but penetrates the material.

•Ripstop canvas is a canvas typically evident by a raised grid pattern woven in to it .
•This grid pattern is thicker and a different type of thread called corespun, and provides exceptional strength. Any ripping or tearing of the canvas is slowed down or stopped by this exceptional strong corespun thread.
•Core-spun yarn or thread is constructed by spinning a sheath of the naturally short cotton fibres around a continuous core of high strength polyester filaments. With the continuous polyester filament core along the yarn, core-spun will have a much higher tensile strength than standard cotton/polyester blended yarn.
The base material fabric of ripstop canvas is either conventional poly/cotton or in some canvases the base material fabric is woven from corespun poly/cotton yarn or thread.
•Ripstop canvas is typically used for 4WD canopies, truck tarps and transport tarps. It is not required for swags, tents etc, however you will find some as such.

•Fresh new cotton/polyester blend & cotton canvas WILL shrink when exposed to moisture or rain for the first few times.
•'WARP' SHRINKAGE:- ('Warp' is the lengthwise or longnitudinal thread in a roll)
  50/50 Cotton/Polyester canvas :--Typically in the region of 2-3% maximum (20-30mm per metre!!!)
  100% Cotton canvas:--------------Typically in the region of 5-6% maximum (50-60mm per metre!!!)
•'WEFT' SHRINKAGE:- ('Weft is the 'weaving' thread across the width of the roll)
                                                       Typically <0.5% (<5mm per metre)

•moisture (causes mould)
•storing canvas on concrete floors (mould, acidic effect, insect infestation)
•dirt left on canvas (acidic effect)
•UV degradation
•abrasive cleaning
•bird-droppings (acidic effect)
•rats and mice eating the canvas

•BRUSHING: Only use a very soft haired brush as any harsh brushing, rubbing or scrapping will damage the material.
•WASHING: If you feel you must wash the canvas, then only wash it down with cold water UNDER NO PRESSURE with the assistance of a soft haired brush or broom.
•MOULD: If mould has developed on the canvas you should set up the tent or annex in the strong sunlight and wipe/brush the mould or mildew off as soon as possible. If you have persistent mould, please contact me for further advice

•A new canvas tent or swag needs to be ‘weathered’, meaning it must be wet down thoroughly and allowed to air dry a couple of times to both SHRINK the canvas and tighten the canvas around the stitch holes. The primary reason is to shrink it tight at the needle hole locations (This weathering in addition to a good quality poly/cotton thread being used should stop the leaking as the cotton in the thread itself should swell when wet). The canvas may shrink anywhere up to 2 - 6% in the warp direction depending on the type of canvas used.... see 'Canvas Shrinkage' above
•Best method is to put your tent or swag up (take out the mattress) and let it get a thoroughly good soaking from the rain a few times. Other way is to thoroughly soak it through with a hose (from a soft spray, not a forced spray) a couple of times.
•Don’t wait until you are out camping waiting for your first rain to get it weathered because you will probably be disappointed as it will probably leak through the stitch holes for a while.

•Over a number of years the canvas material itself will lose its waterproofing. This will be evident by wet patches on the canvas remaining after rain, the underside of the canvas getting wet and a general dry/dusty feel of the canvas. UV protection will diminish over the years, however reproofing will not restore this.
•You can buy good quality canvas water proofer from the larger camping stores in 2 and 4 litre cans. This should be a very thin consistency such that when applied it will soak right into the material between the weave and into the material itself. If required, thin the liquid down with the recommended thinner. (What you don’t want is a thick liquid that applies like a surface paint).
•Before reproofing, remove dirt as much as possible. The reproofing treatment will ‘seal’ in any remaining dirt. Also treat and kill any mould before reproofing.

•DO ensure it is ‘bone-dry’ before storing (as mould will quickly grow if damp)
•DO remove bird-dropping and dirt before storing.
•DO use rodent baits in area where canvas is stored
•DON’T store canvas damp
•DON’T store canvas on concrete
•DON’T use detergents (detergents will wash out the water proofing)
•DON’T use bleaches
•DON’T use water under pressure (will force the water proofing compounds out)
•DON’T use warm or hot water (will wash out the water proofing)
•DON’T use medium or hard brushes (will be abrasive on canvas).

•Canvas comes in a variety of weights, commonly in the range of 8-10-12-14 ounce. The weight refers to the mass of the loomstate fabric per square yard (36” x 36”), after weaving & before proofing. It is becoming more common now that some weights are listed as “gsm” or “grams per square meter”, eg. 12oz yd2 = 407 gsm
•"Confusion No.1”:- A 12oz canvas (loomstate) may weigh approximately 15oz once proofed. It still should be stated as a 12oz canvas, not a 15oz canvas.
•“Confusion No.2”:- What is stated as a 12oz canvas (loomstate) may not weigh exactly 12oz. Different manufacturers and types of canvas will vary in weight, and it is common for say a 11.6oz or a 12.2oz canvas to be abbreviated as a 12oz canvas.
•“Confusion No.3”:- It is not uncommon to hear people talking about 14oz canvas when in fact it may only be 12oz. This occurs for 2 reasons:-
(i) because of “Confusion No.1”
(ii) because 12oz canvas weighs 12oz over a square yard (36”x36”) where the same canvas would weigh approximately 14 oz over a square metre (39.6”x39.6”)... a mix up between an imperial weight and a metric measurement. This confusion sometimes occurs when buying a finished product such as a swag or tent and the information supplied to the salesman may be incorrectly listed as 14oz by the manufacturer.

•Fitment issues arise for 'tailor-fitted' items (eg. 4WD canopies or trailer covers over rigid frames) when this potential shrinkage is not allowed for in manufacturing when the canvas is to be exposed to moisture. Canvas can shrink over such rigid frames to the extent that it can stress tear, pull stitching apart at seams or zips will not close. Correct final fitment is possible by designing the potential shrinkage into the design.
•When joining canvas sections a weft edge should be joined to a weft edge, and a warp edge should be joined to a warp edge where possible. Uneven shrinkage issues arise when canvas sections are joined with a warp edge joined to a weft edge (shown in opposite diagram), as the warp direction may shrink 2-6% and the weft only 0.5%, resulting in a 'puckered' join after being exposed to moisture. Sometimes such joins are unavoidable, however joins should not be done in this manner simply to economise on material.