Impregnating fabric and waterproofing fabric may seem the same, but there is an important difference between them. Impregnation means treating the fibres of the fabric with a substance that causes water to bead up and roll off, whilst “waterproofing” suggests that the material becomes completely impermeable. In practice, when it comes to outdoor textiles, the focus is almost always on water repellency, not absolute waterproofing. In this article, we answer the most frequently asked questions on this topic, so that you know exactly what your fabric needs.
What exactly changes when your fabric is impregnated?
When you waterproof a fabric, you treat the fibres with a substance that creates a water-repellent layer. Water droplets can then no longer be absorbed into the material, but roll off it in beads. This process is also known as the “lotus effect”. The fabric itself does not change in structure, but it does behave fundamentally differently when it comes into contact with moisture.
Before treatment, tent fabric absorbs water like a sponge: the material becomes heavy, dries slowly and is susceptible to mould. After impregnation, the fabric remains light, dries quickly and dirt is less likely to stick to it. The impregnating agents used for this penetrate right into the fibres themselves, meaning that the protection is not just on the surface but also strengthens the structure of the material.
That is also why a good impregnation treatment lasts longer than a superficial spray. The deeper the treatment penetrates the fibres, the longer-lasting the effect.
What does ‘making waterproof’ mean in relation to tent fabric and boat covers?
In the case of tent fabric and boat covers, “making waterproof” effectively means repairing or reinforcing the water-repellent layer, not creating a completely impermeable barrier. Outdoor textiles are not naturally 100% waterproof, but are designed to repel water through a combination of a tight weave and a treated top layer.
When that top layer wears away through use, washing or exposure to the sun, the fabric loses its ability to repel water. As a result, rainwater no longer runs off but is absorbed. By re-impregnating the fabric, you restore that functional water-repellent layer. This is what people mean when they say they want to “waterproof” their tent or boat cover.
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What is the difference between water-repellent and waterproof?
Water-repellent means that water beads up and rolls off the surface, but the material is not completely impermeable when subjected to sustained pressure or prolonged rainfall. Waterproof means that water cannot penetrate the material under any circumstances. Tent fabric and boat covers are generally water-repellent, not completely waterproof.
This distinction is important for your expectations. An impregnated tent fabric will keep out a normal rain shower perfectly well, but in the event of extreme rainfall or if the fabric is under constant pressure (for example, due to contact from the inside), moisture may still penetrate. This is not a fault of the impregnating agent, but a characteristic of the material itself.
True waterproofing is found in materials such as PVC or coated nylon, where the coating seals the entire surface. With canvas and woven polyester, it’s always a question of water repellency. If you understand this difference, you’ll also have realistic expectations when using a waterproofing spray on your tent.
When should you re-waterproof your canvas?
You need to re-waterproof the fabric if water no longer beads up but is absorbed by the material. Here’s a simple test: sprinkle a little water onto the fabric. Do the droplets form beads that roll off? If so, the waterproofing is still effective. Does the water soak into the fabric? If so, it’s time for a fresh treatment.
In practice, there are a few situations where you need to pay particular attention to this:
- After cleaning: Cleaning products can damage the water-repellent layer, meaning that the cloth must always be re-impregnated afterwards.
- At the start of the season: After winter storage, it’s a good idea to check the water repellency before you set off.
- After intensive use: Friction, sunlight and dirt gradually wear away the protective layer.
- If the canvas has been left out in the rain for a long time: Prolonged exposure to moisture accelerates the wear and tear of the waterproofing.
There is no fixed time limit for re-impregnating canvas or polyester fabric. The water test is the most reliable way to assess whether this is necessary.
Do you need to clean the fabric before waterproofing it?
Yes, you should always clean the fabric thoroughly before waterproofing it. If you apply the waterproofing agent to a dirty or mouldy fabric, the agent will not penetrate the fibres properly and the protective layer will not adhere effectively. Dirt and deposits form a barrier between the fabric and the waterproofing agent.
Cleaning and waterproofing are two separate steps that complement each other. First, remove all dirt, including green deposits, mud and surface grime. Then allow the fabric to dry completely. Only once the fabric is clean and dry should you apply the waterproofing agent. Some waterproofing agents also work on slightly damp fabric, but always check the instructions for the product you are using.
Never skip the cleaning step, even if the fabric looks clean on the outside. Fine dust, sun cream and other invisible residues can significantly reduce the effectiveness of a waterproofing spray for your tent.
Does one impregnating agent work for all types of fabric?
Not every waterproofing treatment works equally well on all types of fabric. Most modern waterproofing treatments are suitable for common materials such as canvas, polyester and nylon, but their effectiveness can vary depending on the fabric and the product. Always check that the waterproofing treatment you choose is suitable for the specific material of your tent or boat cover.
Canvas is a thicker, more natural material that requires formulas which penetrate more deeply. Polyester and nylon are more synthetic and have a different fibre structure. A universal waterproofing treatment often works well for both, but for best results, it is better to choose a product specifically designed for your type of fabric or one that explicitly supports multiple materials.
Also bear in mind the method of application: some products are designed for use with a spray bottle, whilst others are worked into the fabric or applied with a cloth. The method of application affects how deeply the product penetrates the fibres and, consequently, how long the protection lasts.
How Rokimi helps with waterproofing your canvas
Here at Rokimi, we have developed a comprehensive range specifically designed for outdoor textiles such as awnings, boat covers, canopies and convertible tops. Our products are ready to use, do not need to be diluted and work on canvas, polyester and nylon. This makes our range accessible to both beginners and experienced campers and water sports enthusiasts.
Our three-stage process ensures a complete care cycle:
- Hood & Tent Shampoo: effectively removes green deposits and light soiling from the fabric surface.
- Heavy Duty Cleaner: tackles stubborn stains, mud and ingrained dirt that are deep within the fibres.
- Hood & Tent Protection: the most effective waterproofing treatment of its kind, which makes the cleaned fabric optimally water-repellent and protects it against rain and damp.
By following the steps in the correct order, you will not only clean effectively, but also ensure that the impregnation adheres as well as possible and lasts for a long time. Take a look at our full product range or find out which applications our products are suitable. Would you like to find out more about our approach? Then visit rokimi.com for further information.
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VIEW ALL PRODUCTS →Frequently Asked Questions
Can I waterproof my tent without washing it first?
It is strongly advised not to apply a waterproofing treatment without first cleaning the tent. Invisible residues such as fine dust, sun cream or sweat form a barrier that prevents the treatment from penetrating the fibres properly. Even if the tent looks clean, a thorough clean using a suitable fabric shampoo is always the right first step for long-lasting results.
How long does the waterproofing process take before I can use the tent again?
Drying time varies depending on the product and weather conditions, but most waterproofing agents require at least 24 hours to dry and cure completely. Some products activate better when exposed to heat: a dry, sunny day or a short spin in the tumble dryer on a low heat setting can speed up the process and improve adhesion. Always check the product instructions for the exact drying time and activation method.
What if my canvas already has mould patches — should I treat those first?
Yes, mould patches must always be removed before waterproofing. Mould damages the fibre structure of the fabric and prevents the waterproofing agent from adhering properly. To do this, use a specialised cleaner such as a Heavy Duty Cleaner, which penetrates deep into the fibres and effectively removes mould and green deposits. Waterproofing is only effective once the fabric is completely clean and dry.
Can I also use a waterproofing spray on a convertible roof or boat cover?
Yes, most high-quality waterproofing products for outdoor textiles are also suitable for convertible tops and boat covers, provided the material is canvas, polyester or nylon. Do ensure, however, that you choose a product that is explicitly stated to be suitable for these applications, as exposure to UV radiation and salt water in the case of boat covers places additional demands on the protective coating. Products specially developed for outdoor textiles, such as those from Rokimi, are ideally suited for this purpose.
How many coats of wood preservative should I apply to achieve the best result?
For most tarpaulins, a single, even coat is sufficient — provided the tarpaulin has been thoroughly cleaned beforehand and the waterproofing agent is applied correctly. For heavily worn or older fabrics, a second coat applied after the first has dried can significantly improve protection. Make sure you always apply the treatment evenly and do not miss any areas, as uneven application leads to uneven water repellency.
Does the fabric lose its breathability after being waterproofed?
No, a high-quality waterproofing agent does not affect the fabric’s breathability. Unlike waterproof coatings, which completely seal the surface, a waterproofing agent treats the individual fibres without blocking the fabric’s microstructure. The fabric therefore remains moisture-permeable from the inside, whilst water beads off the outside — which is essential for comfort in a tent or under a boat cover.
What is the most common mistake made when waterproofing a tent or boat cover?
The most common mistake is skipping the cleaning stage, or applying the waterproofing agent to a cloth that is not yet completely dry. Both mistakes prevent the agent from adhering properly, resulting in a shorter duration of protection and uneven water repellency. Another common mistake is using a product that is too general-purpose and not suitable for the specific material, resulting in the protection being less effective than expected.
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