Canvas comes in different weaves, weights, and treatments. It is important to understand the different canvas specifications because each will determine how well your tent will meet your needs.
The 2 most common weaves used in canvas wall tents are single-fill and double-fill. Single-fill canvas is a looser weave than double-fill. Most single-fill tent canvas is not treated (with the exception of tents made by Montana Canvas and sold by Cabelas). Although single-fill may feel thicker, that is only because it is woven less tightly. Single-fill generally has a lower tear resistance than double-fill, and will shrink up to 10% once it gets wet and dries. Double-fill canvas is stronger, more naturally water repellent due to the tighter weave, and normally shrinks less than 2%. Another way to understand the differences is by using thread count. Double-fill canvas has a higher thread count than single-fill canvas
The most popular canvas weight for tent making is 10.10oz canvas. This refers to the weight of the canvas per square yard before any type of treatment is added. Treatment can add 10-40% more weight to the canvas. The 10.10oz canvas is a nice compromise between strength and tent weight. Although the old 17oz army tents were definitely durable, it usually took an army to set one up because they were so heavy! Most people want a lighter tent that is easier to pack and set up. Few companies are making heavier tents these days. However, a 12oz canvas provides more durability and insulation than a 10oz canvas. Our line of Magnum tents are made with 12oz double-fill army duck canvas. This makes for a strong and weather-resistant canvas. The downside is that it is 20% heavier than 10oz.
There are several types of treatments available to make tents water resistant and/or flame retardant. The only way to make canvas waterPROOF is to use a heavy paraffin wax or PVC coating that also renders the canvas unbreatheable. These types of treatments cause condensation to build up on the inside of the tent. These treatments also add a lot of unnecessary weight to the canvas. Some people prefer to purchase untreated tents and treat the canvas themselves with Thompson's water sealer or Canvak. Although this is possible, it usually costs more to treat the tent yourself than to buy it treated. The best canvas treatment is a dry treatment that is applied to the canvas during the manufacturing process. The result is a lightweight, invisible treatment that has saturated all of the canvas fibers. Many people call this a "Sunforger" treatment. However, Sunforger is a brand of treatment rather than a type of treatment. There are other dry treatments available that achieve the same result. A more generic term for this type of treatment is called "Marine treated". This treatment is designed to last for many years of hard use. Although it may begin to wear off eventually, it is usually not necessary nor advisable to re-treat your tent because the double-fill weave that it is applied to will continue to provide a very high level of water resistance due to its tight weave.
An untreated canvas will still shed water. However, it will be more prone to mildew if it stays damp for extended periods of time. It will also shrink more than a treated canvas. Regardless of whether your canvas is treated or not, if you store it away wet, it will mildew and be ruined!
A tent that is treated with fire retardant does not mean that it is firePROOF. Rather, the fibers are treated so that if exposed to a heat source it will only burn or smolder rather than burst into flames. Once the flame is removed the tent will stop burning. Although not necessary, this treatment does add peace of mind for those using a wood stove, particularly when sleeping.
Before you purchase a tent, be sure and ask which type of weave, weight, and treatment it is you are buying. A 12oz double-fill canvas with a dry treatment, like the canvas used in our Magnum Tents, is the best canvas available for your wall tent.