Canvas is a strong and versatile material, but it is not waterproof.
There are varieties that are pretty water-resistant, such as waxed canvas, but under usual circumstances, canvas is not waterproof.
Canvas is a plain-woven fabric that is usually made out of cotton or linen.
It is a durable and sturdy material, and if thick and strong lines are used to make it, then it can also be pretty heavy duty too.
A blend of cotton and synthetic fibers often makes the canvas a little more water-resistant, and even very close to waterproof, but never fully waterproof.
How to Tell If Canvas Is Waterproof?
If you’re wondering if your canvas has been treated with a waterproof spray here is a simple way to test:
Gather up your canvas and create a water balloon shape. Pour water into the canvas balloon the same way you would pour water into a jug.
Hold the canvas balloon with water in.
If the canvas is waterproof, you will be able to hold the water indefinitely (as if it were in a glass jug).
However, in most cases, you will see the canvas balloon shape start to drip water.
The faster the drips appear, the less water-resistant the canvas is.
What if the canvas balloon shape you filled with water doesn’t drip, does that make it waterproof?
No, the final test is to get a dry piece of toilet roll and dab the outside. If the outside is dry and the toilet roll absorbs no fluid, then the canvas is waterproof.
How Canvas is Created
The lines of cotton, linen or synthetic fibers are woven into the canvas material.
The closer and tighter the weaving is, then the more water-resistant the material becomes.
However, manufacturers cannot make it too tight because then the material would be very rigid and more prone to damage from sharp objects.
How close the weave is will matter because a looser weave makes the material less water-resistant.
Imagine somebody knitting a jumper.
If the knitted loops are very wide and open, then water will seep through very quickly, if the loops are very tight, then water will take a little longer to seep through.
In fact, very tightly knitted clothing and wool clothing can be both very warm and very water-resistant.
Nevertheless, the same rules apply for canvas material, the looser the weave, then the more easily it allows water to seep through.
The Size of the Threads
Let’s say that you have threads that are the size of shoelaces, and they are woven together tightly.
Then, you have another piece of canvas with threads the width of fishing wire, and they too are woven together very tightly.
As you may imagine, the canvas with the fishing wire-sized lines will be more water-resistant.
This is because the weave itself creates holes that water can seep through.
When you use a very wide and large line, the weave itself has plenty of space for holes.
When a very thin line is used, the holes between each woven bend are much smaller.
The Layers of Woven Fabric
Let’s say that your canvas is not just one layer of canvas.
What if it is several thin layers that have been sown together.
The way they are sewn together is going to affect how water resistant they are.
Also, the number of layers that the canvas has will also affect how water resistant it is.
The rule of thumb is that more layers makes for a more water-resistant material.
The Materials Being Used
A pure synthetic line will not allow water to pass through.
In most cases, a synthetic wire will not allow water through.
Though, in the case of canvas, the wire often gets old and starts letting water through.
Cotton and linen will allow water through.
It is a slow process, but the fact it allows water through is another reason why the material is not waterproof.
You may think that if your canvas is made out of 100% synthetic materials, then it must be waterproof because synthetic materials don’t allow water to pass through them.
However, as mentioned, if it is old or worn, then the synthetic material may allow water through.
Plus, as mentioned earlier in this article, the weave itself is what lets water through.
It may only offer microscopic holes in the material, but there are still tiny holes in it that will make it water-resistant but not waterproof.
This doesn’t even take into account the stitching in the canvas, which usually makes the canvas even less water-resistant.