removing mildew from a Cotton tent.

Mould and mildew are fungal infections that attack organic fabrics. We need to stop them from spreading and kill them.  Most of the experts aren’t very optimistic about getting rid of them without calling in the professionals. Mould and mildew aren't identical, but for our purposes I'm going to use the terms interchangeably.

The cheapest options are –

• Vacuum. 
• Scrub with water – Sounds like hard work.
• Vinegar 
• Vinegar and Baking Soda

Then there are a couple of inexpensive household products

• Vanish Oxy Clean
• Dettol Mould and Mildew remover (or equivalent)

And finally I came up with a few possibilities of my own:

• Hypochlorite
• Steam Cleaner
• Pressure Washer
• A UVC light source

Vacuuming

This is the first part of the process.  Removing the loose spores from the surface of the tent will slow their spread and make subsequent processes more effective.  Vacuuming alone won't completely remove black mildew, but it's a useful initial step.

Scrub with water

If the mildew hasn't really dug in, scrubbing is an option, but it's a lot of work, needs to be dried thoroughly afterwards and it's rarely completely effective.

Vinegar or vinegar and baking soda.

Lots of people recommend this, so I'll certainly give it a go.  A little scrubbing with vinegar, or a vinegar/soda paste is often recommended as a way to remove mould.  I assume the mould must be slightly alkaline or something.

Vanish Oxy Clean

Professionals remove mould using peroxide.  This Oxi-clean stuff supposedly has a similar effect on mildew stains.

Mould and Mildew Remover

amazing stuff on tiles and other hard surfaces, it contains 20% sodium hypochlorite.  It's harsh on cotton, but I only plan to use it once.

Hypochlorite

Since the commercial products contain Sodium Hypochlorite and I have some for use in the garden, if the Dettol doesn't fully remove the stains I might step it up a level and use some of this.  Again, it's harsh on cotton so I won't use it if I can clean the tent in a gentler way.

Steam

I have a steam cleaner which is good for cleaning around the house.  It's definitely worth having a try to see if it works on mildew stains.

Pressure washer

This is how I clean up ingrained stains and fungal growth around the garden.  It's very effective, but maybe a bit violent for a cotton tent.

Using UVC Light to kill mildew

You’ve probably heard of Ultraviolet Light – that’s light with a smaller wavelength than the violet that we see at the inside of a rainbow.  It's sub divided into three main categories - UVA, UVB and UVC

UVA

We’re exposed to lots of UVA light (400nm to 320nm) just from the sun and most sources of normal white light.  It’s the stuff that makes us go wrinkly as we get older.  UVA is used to attract insects.

UVB 

UVB is higher frequency – 320nm to 290nm – and this causes sunburn and skin cancers.  UVB is the type of light used in sunbeds.

UVC

is even higher frequency 280-100nm.  It’s even more energetic than UVB, so exposure increases the risk of cancer and also damages the eyes.  Don't be careless with UVC. It doesn’t occur naturally on the earth because our atmosphere filters it out but when created it is an excellent germicide and will destroy mould and mildew spores.  

I’ve already got skin cancer so I’m going to try everything else before going down this route – but it's a useful tool to keep in reserve - and I thought it worth mentioning.  I priced it up and I can get a fluorescent UVC bulb and holder for about fifteen pounds.

The UVC light should be placed close to the tent wall for around an hour to kill the spores, then moved to another section and the process repeated.