Waterproofing Tarps

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Turgolanas
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Waterproofing Tarps

Post by Turgolanas »

I just dyed a 6 by 8 canvas tarp, and am looking at waterproofing methods. Anyone have any advice/good recipes? So far I am considering:

1. Oilcloth (linseed oil and mineral spirits
2. Pure Beeswax
3. Paraffin/other types of wax
4. A mix of the two (I have seen some people use a mix of wax and linseed oil).

Leaning towards oilcloth due to cost/ease of application, but I am concerned about the spontaneous combustion issue, especially with Texas heat and in a drought.

Also, any good ways to apply wax to linen/canvas would be appreciated.
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ForgeCorvus
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Re: Waterproofing Tarps

Post by ForgeCorvus »

I wouldn't use paraffin wax or anything else using hydrocarbons, if you're going to use a modern product you might as well go for silicon.

Boiled linseed oil is an medieval Industrial technology. Once the tarp has cured the exothermic reaction is over and therefore unlikely to spontaneously combust, it can and will burn should it get too close to flames etc but then so will a lot of stuff.

Bee's Waxing a large area is probably easier if you make up a 'slush' of wax and turpentine (real stuff not substitute) and apply like its boot polish. The coating can develop thin spots at folds and flex points so you'll need to re do it often.

Either of these will add weight.

I've done both of these processes and I can talk more on how I did them should you wish

I'm interested as to why you feel the need to proof a tent canvas though?

My re-enactment tent is untreated and to date hasn't leaked..... And everyone has heard about British weather
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Turgolanas
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Re: Waterproofing Tarps

Post by Turgolanas »

The curing is the issue with the combustion, approximately how long does it take to cure? If I can watch it I might be able to do it before winter/it rains again.

About how much beeswax would be needed for a 6/9 tarp?

As for proofing the tarp, it is a fairly cheap canvas in part because I want to experiment with weatherproofing on something that's cheap. I have a canvas duster I want to reproof if it works well also. My personal experience with untreated tarp/tent canvas is that it tends to leak, but that may have been because those tents are normally quite old.
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ForgeCorvus
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Re: Waterproofing Tarps

Post by ForgeCorvus »

Is the canvas a fairly close weave or is it a loose weave like a drop cloth?

OK, I'm going to try not to bore you..... Sorry in advance

An exothermic reaction gives off heat, if that heat can't dissipate it can build up to the flashpoint of whatever materials are around.
The flashpoint of linseed oil is 206C or 402F (data sheet Here .

If you have a bundle of cloth soaked with linseed oil and in a fairly warm environment (full sun or a heated room )then it getting over 206C is relatively easy.... However, if you take the same cloth and hang it up in cool shade the heat should dissipate as fast as it is created.
I always peg my oil rags up in a breeze in the shade and have not had any problems.

The best place to work would be something like a carport or a Dutch barn (Pole Barn?), somewhere shaded that the wind can pass through.
This is a messy job and the time it takes for the oil to cure isn't all that easy to predict, depending on a lot of factors. I've made oilcloth in a few days and other pieces of roughly the same size have taken weeks. Cold and damp slow it down, a warm breeze speeds it up.

I tend to hang cloth one edge up, pegged or pinned to a cord. ETA a taught cord, you're trying to prevent sagging.
I will either paint the boiled linseed oil on or dunk the fabric and wring it to get all the fibres wet (if you wring it you will need to smooth all the creases out of the cloth before drying ).
Then leave it hanging for a while, until it stops feeling oily and starts feeling tacky. You don't want to leave it too late as the next thing you're going to do is hang it up the other way to finish curing. This ensures that you don't end up with the bottom edge saturated and the top edge dry......... If you do end up with a dry edge , just treat it again and hang the cloth with that side at the bottom.

Use only Boiled linseed oil and don't dilute it.
The Boiled oil has additives to speed up the cure (it used to be lead oxide and a few other nasty things, its now less nasty stuff, but I still don't use it on food related stuff).
Diluting it makes it easier to apply a thin coat and can cause it to dry before its cured, this is not what you want.

You can clean up uncured linseed oil with washing up liquid, this is also the best thing to wash your hands and any brushes with. Launder your clothes as soon as you're finished otherwise you could end up with a waterproof patches on your tshirt.

Tomorrow, I'll bore you with Beeswax
Last edited by ForgeCorvus on Tue Aug 09, 2022 7:08 pm, edited 1 time in total.
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Elleth
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Re: Waterproofing Tarps

Post by Elleth »

This ensures that you don't end up with the bottom edge saturated and the top edge dry......... If you do end up with a dry edge , just treat it again and hang the cloth with that side at the bottom.
A strong second for rotating every so often. I have learned. :mrgreen:
Note that darker edge on the left side from when I did not heed that advice. (and I'd never heard the bit about not diluting - thank you ForgeCorvus!)
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ForgeCorvus
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Re: Waterproofing Tarps

Post by ForgeCorvus »

Elleth: Did you just hang it by the corners?
Pinning or pegging it to a Taught cord would prevent the fabric from ending up with that much curve.
It works much the same way as Tenterhooks did when fulling wool
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Elleth
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Re: Waterproofing Tarps

Post by Elleth »

I did, but the curve worked itself out in time. The hassle was that the oil gathered on the bottom edge, so that the top was a bit sparse and the bottom was too saturated. I ended up just leaving as is. It's a nice extra groundcloth for puttering around with when I'm wanting to be able to sit for a while away from ticks in the grass but not actually carry much.
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Re: Waterproofing Tarps

Post by Iodo »

Late reply, sorry

ForgeCorvus wrote: Mon Aug 08, 2022 6:42 pm I'm interested as to why you feel the need to proof a tent canvas though?

My re-enactment tent is untreated and to date hasn't leaked..... And everyone has heard about British weather

if it's made of a good tight weave canvas it will work fine as it is, but it will be as heavy wet as a proofed tarp is dry, but a proofed tarp will keep your blanket dry in a bed roll and work as a ground cloth, so I guess it depends...

Turgolanas wrote: Mon Aug 08, 2022 7:46 pm As for proofing the tarp, it is a fairly cheap canvas in part because I want to experiment with weatherproofing on something that's cheap. I have a canvas duster I want to reproof if it works well also. My personal experience with untreated tarp/tent canvas is that it tends to leak, but that may have been because those tents are normally quite old.

Boiled linseed oil is probably your best bet for the tarp because it's the most hardwearing and long lasting waterproofing, however I wouldn't waterproof a duster with that tho, because you will leave a oily residue on things that you touch and it could damage/shrink the fabric. For the duster just get yourself a tin of barbour or gold label wax, those products are designed for clothing and you'll get good results without risking damaging your coat
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