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I've sung the praises of my trusty canvas bell tent here before, but I wonder if it now needs some TLC.  It's heavyweight canvas (400gsm), from www.armytents.co.uk, and for the last 5 years it's been fine.  Even in a storm (whenever we've camped, we seem to get either a heatwave or a storm or both.  Nothing in between.) , it's been fine.  No matter how much we touch the inside of the canvas, fine, no problems - the canvas swells up and the fibres plug all the gaps like they're supposed to, and the inside of the canvas still feels dryish.  The thickness of this canvas means we feel warm and the rain makes a nice sound.  We have sisal guy ropes which shrink quite a lot in the rain so I do have to adjust the guys when there's a weather change.

Anyway, last week during one very heavy storm (after we'd been lying in bed with the door open watching the lightning!), I saw just a few beads of water appearing along a seam.  This was probably something to do with my inexpert first attempt at pitching a tarp as a porch,. which caused the tarp to run-off onto the side of the tent.  The inside of the canvas nearby still felt dry - it was just a few beads and they soon were either absorbed into the canvas or disappeared.  Slightly more disconcerting were the couple of drops which fell down from the panel taking the force of the driving rain - although again, the inside of the canvas felt OK and I didn't need to take any action.  It didn't seem like a critical situation but I'm worried that it might get worse if I don't do something - after all, it's not happened before and although the run-off from the awning is a new element, the other panel has been through storms just as heavy before.' Obviously next time I'll be a bit more careful about how I rig the awning up.

So, is it time to break out the NikWax, or do I risk damaging the canvas's natural properties by doing this? 

I phoned the vendors, and their helpful technical person said that the canvas is all pre-treated with something like Mesowax (although my web searches suggest this is now discontinued) and that NikWax would be a good thing to use.  Albion Canvas also recommend Nikwax and if they're prepared to flog it to go on their pricey tents, presumably it's not too bad.  The person I spoke to at armytents said that in theory canvas shouldn't need waterproofing because of the natural features of the fabric, and that perhaps the pre-treatment has become universal largely because people nowadays don't understand that a canvas tent needs a good soaking a couple of times before the fabric tightens up properly.  He also suggested that if something is rubbing against an area it may rub off the original treatment on the fabric and leave it leaky.  I'm not sure how all this is consistent with the theory of canvas being naturally waterproof and not needing treatment, but would be interested to hear your thoughts. 

A friend has a canvas tent which is 45 years old, has been in her family since it was new and is regularly used.  She said she only waterproofs it when a problem develops and it's only been necessary every 10-12 years. 

Looking forward to hearing what others think,

Angela

Hi, I've read lots of posts on canvas being naturally waterproof, but can still remember that my first cotton/canvas tent circa1954, was available for two prices. The dearer one being water proof. So in my opinion they are all pre treated. I have an expensive canvas jacket that is not waterproof. Some of the cotton tent sites state that the tents have been treated to make them water and rot proof.

We re proofed my first tent after many years, and it never leaked again.

Thanks Raf.  So presumably if they're pre-treated anyway, you don't stand to lose anything by reproofing?  In the sense that, any detrimental effect on the fabric's natural qualities has already happened....  Certainly this Mesowax or equivalent that my tent was pre-treated with, doesn't seem to have stopped it breathing and absorbing water, because it's always been heavier and stiffer when wet and I can feel the difference in the canvas when it's wet.  It's hard to explain - the inside is nearly always dry to the touch (except for last week's rogue drops!), but the canvas can clearly absorb a lot of water.  One explanation I saw for NikWax (I think) said that it repels large drops but not small drops or mist, which would still allow the cotton fibres to absorb water and expand.  I don't know if that's correct or not, though, as I have forgotten where I saw it & so can't check it out. 

 Another complicating factor is that some products are said to still keep the fabric 'breathable' because they don't plug the small gaps between the fibres, but while air can still move through the gaps in the weave, there is still the issue of whether or not the individual fibres are so coated that they can't absorb water and so swell up. So if you *did* use something which did this, would it would wear off in time? 

What I would really like to know is whether canvas tents historically would have had any waterproofing agents.  I have read about rubbing paraffin on in the 1950s, but was thinking more about grease or wax coatings being used farther back.  What were people trying a few hundred years ago, I wonder?

Cheers,

Angela

Personally i would leave it alone for now, the odd trickle happens from time to time, i have three canvas tents and never waterproofed one yet, all three get regular use and have not let us down yet, and we have camped in some horrendous weather the past couple of years

Take a look at the canvas in heavy rain, any potential future problems will show up as darker patches on the canvas

Quote: Originally posted by caster on 22/7/2009

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.... Take a look at the canvas in heavy rain, any potential future problems will show up as darker patches on the canvas

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Some good points from the above replies.

As an ex employee of a tent manufacturer the natural canvas should swell to remove the holes that would let any water through. however with age, use and expolsure to sun and general wear and tear the canvas fabric will start the age itself. Most Canvas products in recent years (the past 40 or so) do normally have a water resistant finish applied to them in production, this is to reduce the water takeup of the fabric and speed up drying time and reduce the weight when wet.

You can tell if this water repellent treatment is still working as suggested above, if the fabric darkens then water is being absorbed (treatment not working). Another thing to look for is if rain runs off in beads, if not then the repellent treatment requires re applying.

Many treatments that contain silicones or solvents will add a waterproof finish the fabric fibres but don't help the actual fibres last longer, for this Mezowax would have been good but is no longer made. However I have heard that a new product is coming to the market that is designed especially to reproof and nourish Canvas from Storm Waterproofing. Don't think that is in the shops yet but should be around towards the end of the summer, probably just in time to treat tents before they get packed away for the winter.

Hope that helps and clears a few things up.

Hi Angela,

I have had a similar problem while away this July. I have a heavyweight polycotton army arctic ridge and have said dark patches since last year where I removed bird poop (learnt my lesson there).

I had to put the tent up in the pouring rain and as I have to lay it flat while all the poles are inserted into the sleeves it was absolutely sodden when I came to lift it up....once inside I noticed it dripping slowly from one of the dark patches onto the inner....after an afternoon and eve of rain the inner had a damp circle about 20cm in diameter but had not dripped 'through' inner.

I was resigned to the fact that I would HAVE to re proof after putting it off, but for the rest of the holiday, despite plenty more rain I had no further leaks at all.....I can only think that it was the fact it got soaked whilst flat and touching the floor/canvas which allowed water to soak right through as it would if you touch the sides and that although it has obviously lost its ability to repel water in the dark areas , it may not always lead to a leak.

I've decided yet again to leave well alone!..partly due to the cost..partly due to the hassle...but mostly due to the fact that I've never reproofed a tent before and I'm worried I'll do more harm than good!...I'm also sure my tent has been reproofed before as if you rub it even lightly with a cloth, some of the green colour comes off and I'm guessing the product that is applied when new would not come off so easily.

Someone on here kindly pointed out a product I can use on mine which should also give it its colour back but it's not cheap.......

I'm glad that some of my previous post may have been of use.

Just ready through your reply I notice that washing up near the area was mentioned. I could go in to detail but for cleaning and waterproof canvas or synthetic tent material it is aways advisable not to use a domestic detergent as these will remove an of the inherent waterproofness from the surface of the fabric, always use one designed for cleaning waterproof gear as these will leave the repellencey unaffected.

Also reading a couple of the other post people seam to be recommending "weathering" the fabric. This is a very good idea, getting the fabric wet and allowing it to dry as it will help with the waterproofness. Often this may be required after a long period of storage.

I'd make a point of giving it al least one more chance before breaking out the proofer. It's quite possible that it was a pitching problem as you say. If the tarp was shedding extra water onto that spot + your guylines were slackening ina way the canvas wasn't quite taut + the wind was battering at that side, it's quite possible for the capillary action to break at a few isolated spots from sheer pressure. Give it another go, and make sure the canvas is propely taut on that side.

As to the guylines shrinking and bagging well...I remember the olde days of having to go out once per hour to fiddle around with your guy ropes in a storm. It got awafully tedious at 3am. And the new ones give more structural stability in high winds, I think, because your tent doesn't flex around as much. I was delighted when non-shrink guylines were introduced and the only way I'd ever use sisal ones again is if I was doing a re-enactment of some sort. Why not use modern ones? If it's because you want to be authentic as to the original roots of the tent well....a coating of silicon is just as modern, tbh.

Quote: Originally posted by splendidisolation on 31/7/2009

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.I can only think that it was the fact it got soaked whilst flat and touching the floor/canvas which allowed water to soak right through as it would if you touch the sides and that although it has obviously lost its ability to repel water in the dark areas , it may not always lead to a leak.

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Exactly what happened to me once...the inside of the canvas got soaked during erection due to monsoon like conditions and leaked like a sieve. It was fine when it dried out though and has never leaked subsequently.