For canvas, it is best to choose a water-based waterproofing agent that penetrates deep into the fibres and keeps the fabric breathable. For polyester, a lighter impregnation is sufficient to reinforce the existing coating without weighing down the fabric. The material therefore determines which impregnation spray is most effective. In this article, we answer the most important questions about fabric impregnation, from choosing the right product for each material to the correct application process.
What is the difference between canvas and polyester awning fabric?
Canvas is a woven, natural or synthetic cotton-like material that is naturally breathable but absorbs water if left untreated. Polyester is a fully synthetic fabric that absorbs very little water on its own, but the factory-applied water-repellent coating wears off over time. Both materials require impregnation, but for different reasons.
Canvas awning fabric, as found in many traditional awnings and canopies, has an open-weave structure. This makes it breathable and comfortable to use, but also more susceptible to moisture, mould and algae growth. Polyester is smoother and more densely woven, making it less susceptible to biological growth. However, polyester also loses its water-repellent properties due to UV radiation, use and regular cleaning.
The practical difference in terms of maintenance is that canvas absorbs more of the product and requires more frequent treatment, whereas polyester is well protected even with a thinner coating.
Does a waterproofing spray work differently on canvas than on polyester?
Yes, a waterproofing spray works differently on canvas than on polyester. Canvas absorbs the product deep into the fibres, meaning you need more of it and the fabric must be fully saturated for it to work properly. Polyester has a denser structure and absorbs less of the product, so a thin, even layer provides sufficient protection.
With canvas, it is important that the waterproofing agent not only coats the surface but also protects the fibres from the inside out. Otherwise, moisture can still seep in through the back of the fabric. With polyester, the focus is more on restoring or reinforcing the existing DWR (Durable Water Repellency) coating, so that water droplets roll off the surface again.
A universal waterproofing treatment suitable for both materials offers the greatest flexibility, especially if you have several items of kit made from different materials.
Which waterproofing spray is suitable for canvas?
For canvas, choose a waterproofing spray that penetrates deep into the fibres and keeps the fabric breathable. The product must be water-based or specifically designed for thick, woven fabrics. Avoid products that form a hard film on the surface, as this blocks the fibre structure of the canvas and reduces its breathability.
When making your choice, please consider the following features:
- Penetrating action: the product penetrates the fibres rather than simply forming a surface layer
- Suitable for heavy fabrics: Canvas is thicker than polyester and requires a product that can cope with it
- Breathable after treatment: The canvas must not lose its moisture-regulating properties as a result of the impregnation
- Protection against mould and green deposits: Canvas is more susceptible to biofouling, so extra protection is a plus
Apply the product to a clean, slightly damp cloth for best results. Dry canvas does not absorb the product as well.
Which waterproofing spray works best on polyester?
For polyester tent fabric, it is best to use a waterproofing spray that restores the DWR coating and makes the surface water-repellent without weighing the fabric down. Polyester does not require a thick layer, but it does need a product that adheres well to the smooth, synthetic fibre structure and is resistant to UV radiation and weather conditions.
Good impregnating agents for polyester are characterised by:
- Quick overview: Polyester is less absorbent, so the product must adhere to the surface quickly
- UV resistance: Polyester tents are often left in the sun for long periods, so UV protection helps to extend the life of the waterproofing
- Light application: A thin, even coat is sufficient and prevents smudges or streaks
- Versatile: Many polyester items also have seams and zips; choose a product that protects those parts as well
Polyester is slightly more forgiving than canvas when it comes to choosing a treatment, but a product specifically designed for outdoor fabrics always gives better results than a generic water-repellent spray.
How do you apply waterproofing spray to tent fabric correctly?
Apply the waterproofing spray to a clean, slightly damp cloth, preferably outdoors on a cloudy day without direct sunlight. Spray the product at a consistent distance of approximately 20 to 30 centimetres from the cloth, working in sections and ensuring full coverage without overloading the cloth with product. Then allow it to dry as indicated on the packaging.
A step-by-step guide to properly waterproofing a tent looks like this:
- Clean the cloth thoroughly before you start. Dirt and grease prevent the impregnating agent from adhering properly.
- Keep the cloth slightly damp but not soaking wet. This improves absorption, especially with canvas.
- Spray in even strokes from top to bottom, so you don’t miss any sections.
- Pay particular attention to seams and corners, as that is where most wear and tear occurs.
- Leave the cloth to dry completely before you roll it up or pack it away. Preferably in the open air.
- Apply the waterproofing treatment if necessary by briefly heating the fabric with a heat gun after it has dried, or by leaving it in the sun. This improves the adhesion of some products.
Never work on a cloth that is too hot or too sunny, as this will cause the product to dry too quickly on the surface rather than being absorbed into the fibres.
How often should you re-impregnate tent fabric?
You’ll need to re-waterproof your tent fabric as soon as water no longer beads up and rolls off the surface but soaks into the fabric. As a rule of thumb, treat your gear at least once a season, or after heavy use or a thorough clean. Canvas requires more frequent treatment than polyester due to its absorbent fibre structure.
There are a few clear signs that it is time to re-treat:
- Water soaks into the fabric instead of beading up
- The fabric feels heavy when it’s wet
- Wet patches or damp spots are appearing on the inside
- You have just thoroughly cleaned the fabric using a shampoo or heavy-duty cleaner
Cleaning removes not only dirt but also some of the waterproofing, so a fresh treatment is recommended after every wash. Are you putting your tent or awning away at the end of the season? Then waterproof it before storage, so that the fabric is protected going into winter and you’re ready to use it straight away in the spring.
How Rokimi helps with fabric impregnation
At Rokimi, we have developed a comprehensive range of products specifically designed for the care of outdoor fabrics, including canvas, polyester and nylon. Whether you have an awning, canopy or boat cover, our products are ready to use and do not need to be diluted. This makes them accessible to both experienced campers and beginners who want to make their tent water-repellent for the first time.
Our range of fabric impregnation services includes:
- Hood & Tent Shampoo: for regular cleaning of green deposits and light soiling, in preparation for waterproofing
- Heavy Duty Cleaner: for stubborn stains and ingrained dirt that won’t come out with ordinary shampoo
- Hood & Tent Protection: the most effective waterproofing agent of its kind, which makes the cleaned fabric optimally water-repellent and protects it against rain, moisture and dirt
Together, these three products form a complete care routine: cleaning, deep cleaning where necessary, and then protecting. This ensures your kit is ready for any season. View our full product range, read more about the Applications by material, or go directly to the Rokimi website to find out which product best suits your kit.
Frequently Asked Questions
Can I use the same waterproofing spray on both canvas and polyester?
Yes, there are universal waterproofing agents suitable for both canvas and polyester. Please note, however, that with canvas you should apply more product and dampen the fabric slightly to ensure better absorption, whereas with polyester a thin, even layer is sufficient. A universal product is handy if you have several items of kit made from different materials, but a material-specific product usually gives better results.
What should I do if there are still stains or streaks on the fabric after waterproofing?
Stains or streaks after waterproofing are usually caused by the product being applied unevenly or drying too quickly. Clean the fabric thoroughly again, ensure it is slightly damp, and reapply the impregnating agent in even strokes on a cloudy day without direct sunlight. If necessary, activate the waterproofing afterwards with a heat gun to improve adhesion and even out the stains.
Do I need to waterproof the tent fabric from the inside as well?
With canvas, it is advisable to treat the inside as well, as moisture can otherwise penetrate through the back of the fabric. With polyester, this is less necessary, as the fabric itself absorbs very little water and the protection works primarily on the outside. If in doubt, always treat the outside thoroughly first and check after a rain shower to see if any moisture has penetrated the inside.
Do I need to waterproof a new tent or awning that I’ve just bought?
In most cases, a brand-new tent or awning already has a factory-applied water-repellent coating, but this is not always sufficient for long-term use or extreme weather conditions. It is advisable to waterproof new equipment after the first clean or after the first use, so that protection is optimal right from the start. This will extend the fabric’s lifespan and prevent the original coating from wearing out quickly.
Can I also use waterproofing spray on other parts of my tent, such as seams, zips and pegs?
Yes, seams and zips are actually the most vulnerable areas and deserve extra attention when waterproofing. Seams are often the first place water seeps through when the waterproofing wears off, so be sure to apply more product here. It’s also best to treat zips and then rub them with a zip wax or silicone spray to keep them smooth and waterproof.
What is the most common mistake made when waterproofing tent fabric?
The most common mistake is applying the impregnating agent to a dirty or dry cloth. Dirt and grease prevent the agent from bonding properly to the fibres, resulting in uneven or inadequate protection. A second common mistake is working in direct sunlight or at high temperatures, causing the product to dry too quickly on the surface rather than penetrating deep into the fibres. Always clean the fabric thoroughly first and work on a cloudy day for the best results.
How should I store my waterproofing spray to ensure it lasts as long as possible?
Store the impregnating spray in a cool, dry place away from direct sunlight and frost, as extreme temperatures can affect the product’s effectiveness. Ensure the spray nozzle is tightly closed after use to prevent the product from drying out or becoming blocked. Most impregnating agents have a use-by date on the packaging; for best results, use the product within two years of purchase.