How do I treat a canvas tarp to make it waterproof ?

Answer 1

You can use an oil or wax preparation. It will still leak if it doesn't have enough slope to run water off or if somebody touches the inside. It needs slope to shed water. Otherwise you must treat it as an oilcloth like those australian coats. Messy, heavy and attracts dust.
I have lived in canvas tents and they are still used in Northern Ontario for prospect and bush camps. They are always plain canvas, untreated. You must be careful not to touch them inside if it is raining outside. The plastic tarps will leak as well if they have no slope and water can sit or pond on them.

Answer 2

Get a box of paraffin wax. If you live in the Midwest, most grocery stores have it in the canning section. Just rub the wax all over the canvas and you're good to go. Forget about the gas\oil\wax mixture. That opens up all kinds of trouble. Smell, fire risk, toxicity. Use the wax alone and you'll be fine.

Answer 3

In the old days, they would mix a mixture of gasoline, oil and paraffin wax together then cover the canvas to make it water proof. Obviously this smelled like hell, and was very flameable- so, go to your local camping store, and see what the current version that smells OK and is flame retardant and buy some there

Answer 4

There are several waterproofing sprays available on the market. Or you could rubberize it, coat it with tar, or heatset plastic onto it.

It all depends on whether or not you have adiquate ventilation and/or proper equipment.

Answer 5

scotch guard is water soluble so it won't work but they sell canvass online and it is water proof and expensive in large sizes
canopies are made of water proof materials but steer clear of polyesters they suck..... if u already have ur canvass wax or parafin is an ideal water proofer

Answer 6

Spray scotchgard on it. It will make it waterproof.