How to Clean Mold From Canvas Tents

A lesson on moldy tents and deep cleaning

Posted on: July 18, 2019
By: Robyn Smith
How to Clean Mold From Canvas Tents

You’ve seen it on that last slice of bread, creeping up the bathroom wall, or dusting the outside of a fabulously dry-cured sausage accompanied by an exquisite French cheese. Good or bad, mold is an intractable part of the world we occupy. It can also destroy your stuff. 

First and foremost: Canvas tents have been used all over the world in a variety of environments for 100+ years, remain the undisputed champion in tentage material, and are built to last. You just have to take care of them. Similar to other fine pieces of equipment, tools, and clothing, proper maintenance is required. If you are looking for a long term shelter to leave up in the rainforest without much maintenance, a non-breathable petroleum based product like hard plastic may be a better solution, although comfort and humidity may limit the amount of time you want to spend inside it.

Understanding Mold on Tents

What is Mold?

Mold is a fungus. Unlike plants which require energy from the sun to grow, mold derives energy from degrading organic matter. Without getting too sciencey for a blog about tents: mold excretes enzymes that cause organic materials to decompose (aka “rot”), which it eats to create energy to reproduce, and creates waste, and so the circle of life moves us all. Mold is nature's recycling center, a fascinating and essential component of the natural world that makes our planet livable.

Where does Mold come from?

Mold is everywhere in nature. It clings to clothes, skin, fur, leaves, bugs…you name it, it’s probably got mold on it. Mold can grow just about anywhere that is above freezing. Although mold can grow in a range of environments, it is particularly virulent in damp, dark environments, where there is lots of organic material to feast upon. Think rainforest. Think upcountry Hawaii.

Mold spreads and reproduces by releasing large numbers spores which can easily spread through air or water and colonize new locations. In the right conditions, mold can grow in as little as 24 hours, which is why it’s important to deal with it immediately as soon as you see evidence of it.

Is Mold Dangerous?

Although we at CanvasCamp are not medical professionals, after thorough research, first hand experience, and extensive experimentation we can firmly state that unchecked mold can destroy a tent. In mild cases, mold is unsightly, once mold gets into the fibers of the canvas it is almost impossible to remove it completely, although it is very possible to prevent it from spreading. In extreme cases mold causes rot, holes, tears, and can lead to complete loss of a tent.

In regards to your health, there are a variety of reputable sources that provide extensive information on the possible effects of mold exposure (CDC, WHO). Generally speaking most molds are not dangerous to humans and a healthy person without a specific mold allergy or preexisting condition will be largely unaffected by mold. That said, it’s generally a good idea to avoid living in close proximity to, breathing, or eating large quantities of mold, which is typically the case when mold is visible with the naked eye.

Is my tent mold resistant?

All CanvasCamp tents are made from 100% cotton canvas that has been impregnated with a light treatment to increase water resistance and provide UV and mold resistance. When choosing our treatment we aim to achieve the perfect balance of comfort and durability. The comfort factor is largely influenced by breathability: the heavier the treatment the less the canvas breathes which increases internal humidity. Durability is influenced by the quality and thickness of the canvas, as well as effectiveness of the treatment in combating environmental strain. 

In striking that balance we find that a light, environmentally friendly treatment serves the vast majority of the market in a range of environments. Cleaning and retreating the canvas is an essential part of tent ownership and is highly dependent on total time in use and the conditions the tent is exposed to. As a general rule, 20 weeks of continuous use is a good time to treat the tent. If your tent is pitched continuously in a humid, densely vegetated, or rainy area, you may need to treat the tent after 10 weeks. More information on cleaning and retreatment can be found on our FAQ page.

How do I prevent mold?

For the casual camper or glamper, standard cleaning/retreatment and ensuring that you never pack your tent while it is damp or dirty is all that is needed to avoid mold. Let the tent dry completely in the sun, ensuring the floor, guylines, poles, stakes, and bags are all bone dry before rolling it up for storage. If you can’t get everything dry when breaking camp, loosely roll up the tent for transport and let dry it at home in a garage or living room before storing it.

If you are pitching the tent for a long period of time or living out of your tent, YOU ARE AWESOME! As a seasoned naturist you know the importance of maintaining a clean camp and quality equipment. Follow these tips to prevent mold from growing in the first place:

  • Purchase the Pro or ProTech bell tents which are specifically designed for long term use or extreme environments.
  • Regularly inspect the tent for mold growth (a good time to do this is when you retension the guylines)
  • Clean off any dead leaves, bugs, bird poop, etc. that falls on the tent
  • Cut back vegetation in the surrounding area so tall grass and weeds are several feet away from the canvas. Keep it up as new growth forms. (This also keeps the windows clear and you more comfortable)
  • Keep your tent well ventilated. Mesh covered vents, windows, doors, and even walls on the ProTech make it easy to keep it breezy.
  • Clean and retreat your canvas as needed, based on your observations of the impact the environment is having on your tent.

Note: Cleaning and retreating your tent will involve taking the tent down from time to time. A typical cleaning and retreatment can require a few hours on a sunny day. If you are living in your tent, be prepared to move your stuff out for a deep cleaning a few times a year.

Won’t the sun prevent mold?

Lots of moisture and sunshine provide an excellent environment for plants to grow, and dead plants and moisture provide the ideal environment for mold growth. Over millions of years many types of mold have adapted defenses to damaging effects of sunlight. Additionally, UV light degrades the treatment on the tents, exposing the canvas to the elements, making it more susceptible to mold penetration.

Don’t rely on the sun. Keep your tent clean and retreat it as often as needed.

Should I just go with a plastic tent?

Plastic tents are entirely different creatures than CanvasCamp tents and there are positives and negatives to each. 

Canvas tents do require more maintenance and care than plastic, but are by far more comfortable, sustainable, and durable.

Plastic is non-organic and petroleum based which is less delicious to mold than cotton. This is why plastic doesn’t biodegrade effectively and also why our oceans and landfills are filled with plastic. Nylon and polyester are very difficult to repair and rips and tears are typically fatal. Plastic doesn’t breathe like canvas, which is essential in a humid environment to keep internal humidity at comfortable levels. You can’t use a tent stove in a plastic tent. Plastic tents are still effected by mildew, which stinks, literally.

How to Clean Mold From A Tent

Prevention is key, but mold is everywhere and can happen to anyone. 

Identify it: Mold can come in many shapes and colors but generally on canvas it looks like tiny black, blue, or green specks peppered into the canvas.

Kill it: Spray it with distilled white vinegar. Let dry.

Clean it: Scrub it lightly with a soft brush using a mixture of salt, lemon, and hot water. Avoid using detergent soaps or bleach which is harsh on canvas and tough to rinse out. Let dry.

Retreat it: Spray the clean, dry, canvas with a canvas treatment (we like Ultramar Canvas Protector waterproofing).

Deep Cleaning a Very Dirty Tent

Although mold and mildew prevention is always the best method for maintaining your tent; mold stains do occur, especially in warm, flora and fauna rich environments. If nature has outpaced your tent maintenance routine and you’ve got a very dirty tent on your hands, there is still hope!

First and foremost, keep these things in mind at the outset:

  • Set a realistic expectation: mold stains are extremely difficult to remove entirely. The tent will never look brand new again, but with some hard work and patience a good cleaning can add to the life of your tent.
  • Deep cleaning is hard work and will take a long time. You may need to repeat a few of these steps depending on how dirty the tent is, or how much soap you have to rinse out.
  • Enlist some help! Tents are heavy, wet tents are really heavy
  • If you perfect this process and want to start a bell tent cleaning business in your area; let us know! There is a demand!

Materials Needed to Deep Clean a Moldy Tent

  • A bucket of Oxyclean in powder form, Oxiclean is sodium percarbonate; you can make it yourself but it’s easier to buy the brand name which is generally very affordable.
  • A large container that can fit the tent canopy and water with extra room to stir it and manipulate it. (Suggestions: 55 gallon drum, trash can, large storage bin, etc.)
  • A sturdy stir stick: boom handle, canoe paddle, de-barked tree branch with smooth ends
  • A soft brush or broom
  • An abundant water source (hose)
  • 2 able bodied workers
  • 24-48 hours of favorable weather to complete all the work and allow the tent to dry completely at least twice.
  • Floor Cleaning stuff: a mop and some mild soap, whatever you clean your kitchen floor with works.
  • Canvas Waterproofing solution to retreat the tent so you don’t have to do this again for a while!

Deep Cleaning Process:

  1. Remove all loose dirt and debris with a soft brush or broom
  2. Separate the canvas tent canopy from the floor of the tent. You will wash the floor separately. You can leave the guy-lines on if they are dirty, just remember they must also be retreated in the end to prevent UV damage.
  3. Fill a very large container with about 1 foot (30cm) of warm water. Add several cups of Oxiclean, use your best judgement on how much to use vs. how dirty the tent is and reference the recommendations on the box. Stir thoroughly until the solution is dissolved completely. Warm water dissolves the solution better than cold water.
  4. Place the tent canvas (not the floor) in the container. 
  5. Fill with water until the tent is submerged.
  6. Stir and agitate thoroughly so the solution is well mixed and the canvas is soaking evenly.
  7. Allow the tent to soak for 4-10 hours, stirring occasionally. It’s ok to leave it soaking overnight if you need to.
  8. You will want a clean surface to place the tent on to dry so have your clean floor ready. You can clean the tent floor just like a kitchen floor. Sweep it, mop it, rinse it. 
  9. When your done soaking, dump out the dirty water leaving the tent inside. Oxiclean shouldn’t kill grass but if your concerned just hose off your grass afterwards, the solution to pollution is dilution.
  10. With the container on it’s side, do a quick pre-rise rinse and roll to get the dirty residue off see how the tent looks. If you think it needs another round of soaking, fill up the container and add some more oxiclean.
  11. If the canvas looks reasonably clean, add more water, use your stick to agitate and stir, then dump. Repeat as needed until most of the soap is out of the canvas.
  12. Spread the canvas out on top of your clean tent floor and pitch it. You can also throw the floor on top of a car, then put the canvas on top of that to assist with run off. Don’t put the canvas directly on your car because Oxiclean can strip clearcoat.
  13. Hose the tent down again and be sure get any remaining soap off of it.
  14. Let the tent dry completely. 
  15. Retreat the tent with a canvas specific waterproofing solution of your choice.