Traditional Canvas Tent Waterproofing

• The simplest way to waterproof a canvas tent is to rub the entire surface of the canvas with paraffin, then go over the surface with a hot iron. You can also use a mixture of paraffin and turpentine to make a waterproof canvas coating. Melt 1 lb. of paraffin with 1 gallon of turpentine in a double boiler, then paint the mixture onto a pitched canvas tent. When this waterproofing method is used, the fibers of the canvas absorb the wax, which prevents water from saturating or passing through the fabric of the canvas. Even though there are still tiny holes between the threads of the fabric, the surface tension of the water causes the water to bead and run down the fabric.
  
  

Using Linseed

• Another waterproofing method involves painting linseed oil over the tent. You must allow oil-treated canvas to dry in a shady area to make it waterproof. You must also apply extra waterproofing material to the seams of the tent to prevent water from leaking in. Many canvas tents also include a rain fly, an outer covering on top of the tent that keeps water from entering. Canvas tents must never be laundered in a washing machine, since this type of washing will destroy the waterproof coating on the surface of the fabric.
  
  

Modern Canvas Tent Waterproofing

• There are many modern waterproofing products that you can brush, spray or roll onto a canvas tent. Common waterproofing materials include polyvinyl chloride (PVC), polyurethane and silicone. Many modern waterproofing products are water-based and solvent-free. These products usually must be reapplied every one to three years, depending on how often you use your canvas tent.
  
  

Other Protection

• Many modern tents are made from cotton canvas duck treated with a silicone waterproof coating. However, there are also modern tents made from acrylic canvas with a factory-applied fluorocarbon waterproof coating. Petroleum-based products and products containing fluoropolymers are best for applying an additional waterproof coating on acrylic canvas, since they are compatible with the factory waterproofing. However, you cannot use silicone on pre-treated acrylic canvas, since it will not stick to the fluorocarbon waterproofing. In modern canvas tents, seams are often sealed with liquid urethane. These materials must dry completely to become waterproof.