Do I need to waterproof my tent?
Waterproofing and old tent
Yes, you should waterproof your tent if it is old and leaking or a new canvas or ripstop tent.
An old tent should be waterproofed as the need arises, but waterproofing a used tent or canvas canopy is a risky activity. The risk of failure when sealing a used canvas comes mostly from the sealant that is applied unevenly.
Caravan and tent owners who are not active handymen or women could find that they applied the sealant unevenly which leads to leaking spots.
A sealant that is not applied strictly with the manufacturer’s instructions often fails.
Resealing a tent must be done in the best surroundings. Most of the reseal failures we see have to do with sealant applied unevenly, applied in direct sunlight with the expectation that it will dry quickly but then cracks, or applied in damp conditions that lead to the sealant not drying properly.
There are campers who report that they successfully resealed their tents. Most of them are seasoned DIYers.
We would not advise resealing your old tent if it is your first DIY project.
How do I make a new camping tent waterproof?
A new caravan or camping tent needs to be set up and sprayed well with a garden hose and sprayer.
Canvas and ripstop tents both need this treatment. It is important that you do not use a pressure washer as that subjects the canvas to forces that are rarely encountered in natural rain.
The correct way is to spray the tent in the same way soft rain will fall on it. That allows the canvas to absorb the water without resistance and let the canvas be thoroughly soaked.
This method is required for both traditional canvas and modern ripstop.
How do you seal a tent?
Modern canvas sealant is silicon-based and water-repellant.
Modern tents are mostly made from ripstop which is made from a polyester and cotton blend.
Research showed that a 33/67% polyester/cotton blend provided the highest waterproof properties. Ripstop available in the trade is mostly a 35/65% polyester/cotton blend with a 50/50 ratio also available. Natural latex can also be used as a water repellant but due to the cost implications, it is not used for camping tent canvas.
A silicon-based sealant that is applied according to the manufacturer’s instructions will often be adequate. Factory sealing sometimes involves the silicon being applied at low pressure.
Most canvas resealing is done by hand with paint brushes.
How do I make an old camping tent waterproof?
You can waterproof an old tent but success depends largely on the condition of the canvas.
Traditional canvas tends to get damaged or weakened by any kind of friction. This leads to weak spots and friction stains on the canvas. Another cause of leaking spots on canvas is that people wash their tents with water, soap and hard brushes. Canvas doesn’t like aggressive scrubbing as it damages the fibre.
One place where leakages in tents often occur is the seams. Especially in new tents, a leak during the first rain you encounter can often be found on the seams.
This is the result of the manufacturer using sub-standard thread or a needle that is too thick. A thick needle makes larger holes and if the stitch holes are thicker than the thread, you can be sure that you will have leaks.
Sub-standard thread always means a shorter lifespan, quicker leaks, and seam thread that frays.
Canvas sealant cannot seal fibres that are severed over a large area, because the sealant must then substitute for the fibres. Sealing any material is just a way of repairing the leaking spot, not the material itself.
Conclusion
It is best to take an old tent to a factory or to someone with a proven record of successfully waterproofing tents.
A new tent should be soaked in a light spray for at least 4 hours to enable the fibers to fully absorb the moisture and to allow the fibers to absorb enough for the canvas to seal properly.
Maxcons do not advise the waterproofing of canvas because when canvas starts to leak, the material has been damaged or has perished which means that waterproofing are mostly unsucsesful.
Waterproofing of ripstop is usually more successful and although Maxcons do not do waterproofing as a service, here is advice on how to do it yourself.