How to Waterproof Canvas

If you have a canvas tote bag, backpack, or even a canvas tarp, you know how frustrating heavy rain can be.

Canvas is a durable, flexible, and environmentally friendly material. But unfortunately, it’s not entirely weather-resistant. Once it starts to pour, your canvas and all the items inside can get soaked.

Luckily, canvas is easy to waterproof, so you don’t have to worry about keeping your belongings dry! We’ve got you covered with several step-by-step methods for making your canvas item more water-resistant in no time.

How Waterproof is Canvas?

Canvas is a durable material and is naturally slightly waterproof. During a mist or light rain, your canvas should only get a little bit wet, or the water may not soak through at all.

However, during heavy rain, water will almost always soak and seep through your canvas, wetting all of the items protected by your canvas, and even potentially resulting in mildew buildup. To ensure that your canvas is water-resistant, you’ll need to waterproof it yourself using any of these methods.

Method 1: Wax

An environmentally friendly and natural way to waterproof your canvas is to use wax. You can purchase wax at supermarkets, craft stores, or online, making this a very accessible way to waterproof your canvas!


  • Wax (a blend of beeswax and paraffin waxes are ideal, or there are waxes made just for fabric that you can purchase)
  • Soft-bristled brush like a paintbrush or dauber brush
  • Large pot
  • Smaller pot
  • Water
  • Hairdryer


1. First, you’ll want to test the wax on a small piece of your canvas. There is a chance that wax may change the color or texture of your canvas, so testing the reaction between the materials before applying wax all over the canvas is a good idea. Rub your wax against a piece of your canvas that is small and unnoticeable, in case you don’t like the way it looks. If you are satisfied with any change in color or texture, you can proceed with the wax method.

2. Melt your wax by placing your wax in the smaller pot and putting the smaller pot inside the larger one. Pour boiling water into the larger pot so that it surrounds the pot with the wax in it. To be sure that the wax is melted evenly, you can stir the wax every so often, but wait for the wax to cool down a bit before use. The water around your wax should be warm when the wax is ready for application.

3. Take your brush and dip it into the wax, using the brush to spread the wax over your canvas. Use multiple brush strokes to ensure that you’ve thoroughly applied enough wax to the canvas. Once the wax is applied, work it into the canvas with your hands. You want the wax to be somewhat blended into the fabric of the canvas, not sitting on top of it.

4. Heat the applied wax once more with the hairdryer to ensure that it has thoroughly penetrated the canvas material and will be truly water-resistant.

5. If you’d like to waterproof the insides of your bag or backpack or the other side of your tarp, you repeat these steps with the other side of your canvas. However, the more wax you apply to your canvas item, the stiffer it will become, so only waterproof what you need to if you still want the flexibility of your canvas to remain intact.

6. Dry your canvas either by putting it into a laundry bag or pillowcase and drying it in the dryer for 15 minutes, or by letting it air dry for 24 to 48 hours. For future cleaning, only wash your canvas in cold water and preferably by hand so that the wax doesn’t heat up and melt or become displaced.

Method 2: Water-Repellent Sprays

If you’d rather use a commercial product to waterproof your canvas, many companies sell water-repellent sprays you can use on fabrics and other materials.

This is a quicker and easier process than at-home waterproofing methods, but often contain chemicals that can emit potentially harmful odors and are worse for the environment. This method is also more expensive.

If you’re dead set on the ease of a spray, be sure to purchase a spray without silicone, as the silicone may affect the efficacy of the spray’s water resistance.


  • Water-repellent spray (preferably a fluoropolymer-based spray, as these are most effective)
  • Canvas cleaning materials, such as water and a mild soap or detergent
  • Aluminum foil or tape (optional)


1. Clean your canvas with soap and water before using the spray. This will ensure that the spray does not interact with any other materials on the canvas. Let your canvas dry completely before continuing.

2. If your bag, backpack, tarp, or other canvas item has zippers or other hardware, it may be a good idea to cover the hardware with tape or aluminum foil to ensure that the chemicals from the spray don’t damage the metal on your item. This step is optional, but a good idea if you want to be safe.

3. Test the spray on a small patch of your canvas to check for discoloration or damage. If you’re comfortable with any discoloration or changes to your canvas, you can continue waterproofing.

4. In a place with good ventilation, preferably outside, follow the instructions for your particular water-repellent spray. This will often be to spray two coats of the repellent onto the canvas, the first in one direction and the second coat in the perpendicular direction. Allow the canvas to air dry completely before use so the odors can dissipate.

5. To clean your canvas, follow the instructions on the water-repellent spray. Often this means washing your canvas in cold water, and preferably by hand or in a delicate setting.

Method 3: Alum Powder and Laundry Detergent Powder

Another at-home method for waterproofing your canvas is by using alum powder and laundry detergent powder. If you don’t already have them, you can purchase these materials from a grocery store or supermarket, making this an accessible and inexpensive method as well.

Alum can be toxic, so be sure to wear gloves, goggles, and other protective gear while doing this method.


  • 450 grams of laundry detergent powder
  • 250 grams of alum powder
  • 15 liters of hot water
  • Two large buckets
  • Glass jars or bottles


1. In one of the large buckets, mix all of the laundry detergent powder with 7.5 liters of hot water. Dunk your canvas into the mixture, making sure that your canvas is completely soaked. Leave your canvas out to dry and make sure it is completely dry before the next step. This may be a multi-hour or multi-day process, so be patient.

2. Once your canvas is dry, mix the alum powder with the remaining 7.5 liters of hot water in the other large bucket. Make sure the powder and water are thoroughly and completely mixed. Drop your canvas into this mixture, making sure all of the canvas is completely submerged. Do not remove the canvas.

3. Use the glass jars or bottles to weigh down your canvas and keep it fully submerged in the alum mixture for two hours.

4. After two hours in the mixture, remove your canvas and allow it to air dry in a space with lots of ventilation and airflow.

5. To keep your canvas water-resistant, repeat this method every year or so for the best results, just to maintain the efficacy of the water repellency. For cleaning, wash your canvas in cold water and preferably by hand or in a delicate setting.

The Last Drop

Canvas is a versatile, environmentally friendly, durable option for many types of items, from bags to backpacks, tarps to shoes, and more!

Unfortunately, it is hardly resistant to heavy rain, and your belongings protected by the canvas are bound to get wet if the weather gets bad. Waterproofing your canvas is a cheap and easy process that can be done safely at home and will protect against heavy rainfall!

Keep in mind that although all of these methods are good for increasing the water-resistance of your canvas, your canvas can’t be 100% waterproof. Additionally, water resistance can wear down over time, especially if you are continually washing your canvas item, so you will want to repeat the waterproofing process every year or so, depending on how the waterproofing holds up.

Be sure to take all precautions necessary when handling chemicals and potentially toxic materials, always let your newly waterproofed canvas dry completely before use, and follow the washing directions for your waterproofed canvas. Taking all of these measures will keep you safe and increase the lifespan and efficacy of your waterproofed canvas! No matter which method of waterproofing you choose, the rain will no longer be a problem.