I'm in the planning stages of a tent build. I'm planning to use silnylon for the body. Apparently a number of big tent makers such as Golight have fire resistant silnylon that they use for their tents. Since the plan is to use a ti goat stove in this tent during winter, fire retardent would probably be a good thing. Does anyone know where to get fire retardent silnylon, or if there is a way to treat silnylon to make it tire resistant? Or is there another fabric out there that is compairable to silnylon for weight and such that won't burn quite so easily?

I don't know where to get fire-retardant silnylon, so I don't have an answer to the question you posted. But I just thought I'd mention that silnylon is the most inherently fire retardant lightweight fabric used in outdoor gear. Silicone is among the most heat tolerant of all polymers. It is often the only serviceable option where something elastic is required at temperatures above 500F. Some silicones will tolerate temperatures above 800F for short periods. This is several hundred degrees higher than any other fabric coating material (urethanes, for example.) Nylon, too, is relatively tolerant of high temperatures compared to other synthetic fabrics. It has a much higher melting point than polyester, and it burns more slowly and is easier to extinguish. Cotton or linen might do a bit better, but at a big weight penalty.

You could consider making a "hat" and a tube to go around the woodstove chimney (with a little space in between) out of Kapton film (available on ebay). This would protect the tent fabric from the hot air rising up from the stove, but it wouldn't block the radiant heat. It would be much lighter than the fiberglass heat barriers that some people use with woodstoves in synthetic fabric tents.

That goes contrary to what I've seen for the dangers of silnylon being around fire, now I'm really confused.

Two more questions:
This will be a pyramid style tent with a central pole. I was thinking of lining the very peak with cordora to keep the center pole from punching through, but is there a different method or material that would work better?
What would be the best material to tape the seams in the silnylon, or would that even be necessary?

Ray, sorry for confusing you. I wonder if the warnings you heard about silnylon were meant to be warnings about synthetic fabrics, or lightweight fabrics, in general. Lightweight silnylon is definitely more likely to be affected by heat than cotton canvas, and an ember will burn right through it, but it has better resistance to heat than any other lightweight synthetic (ie, polyester fabrics, urethane coated nylon, or cuben) that would be suitable for a tent.

I haven't made a mid, so, for advice about construction details like the peak and the seams, I'd recommend starting a new thread.

Fire retardant coatings do not "stick" to silnylon as far as I am aware. Most of the silnylon fabrics that have an FR coating are actually coated with silicone on one side of the fabric. The side with the FR coating is usually PU coated. Make no mistake, fabrics coated with FR will burn. The fire retardant simply inhibits a fabric from continuing to burn in the absence of a continuous flame. Silnylon burns quite well.

Are there any disadvantages with the FR silnylon then? Weight, strength, cost, waterproofness? Does anyone know where I can buy this sort of fabric?

It used to be that the PU coat needed for the FR would add considerable weight.
But lately, a number of high end tents are coming out with very light versions of the combo coated nylon, usually around 20 denier. The task would be to track them all down on the web, then see if any company also had tarps in the same material.
Not likely, but if you found one, it could produce enough yard goods for your purposes. Alternatively, consider using a heavier FR material just for that portion of your canopy that will be closest to the heat source. Not too much weight penalty, just a few few extra seams around the heavier material.

One way to make a fabric flame retardant is to make it weaker. The weaker fabric
melts away from the flame faster and goes out. Silicone coating increases the fabric
strength. So if a 20d fabric (lower tear strength than 30d) used PU (which weakens it) it becomes "flame retardant" enough to meet standards.

Flame retardants that are added can be cancer causing
http://californiawatch.org/dailyreport/flame-retardant-added-states-list-cancer-causing-chemicals-13065

I don't like the thought of using weaker fabric, and it's sounding like it would be reasonably hard to get in any quantity. The tarp thing probably would get quite costly. This tent is slightly bigger than a golight Shangri-La 5, and should be capable of sleeping 6. I will need a total of 12 yards of silnylon 64 inches wide. If my math is correct, total weight for the tent body (no pole, floor, or stakes) will be roughly 41 oz.

How would it work to have a curtain of fire retardent fabric designed to catch sparks that would get hung up when the stove is in use? What fabric would you recommend for this use?

The fireproof fabric is Nomex (like what race car drivers use), but you may find it too heavy to be practical.

Thin aluminum foil works OK.

--B.G.--

I know what Nomex is, and that's probably a bit overkill. I'm wondering if there are lighter fabrics that would stop a few sparks from the fire from causing a disaster, not save the tent from a forest fire.

Ray, you have a lot of options for materials below 3oz/yard. Kevlar fabrics actually tolerate slightly higher temperatures than nomex, and they are available in very light weights (but high prices). For stove projects, I have used 0.4oz kevlar gauze, and woven kevlar is available for composite layups in 0.8oz, 1.4oz, and 1.7oz weights.

I have also made windscreens for stoves from Kapton film. It looks and feels similar to mylar, but it has an amber color. It is available on ebay in many weights (from 1 to over 5 mil). I have some fiberglass-reinforced Kapton laminate that is basically high-temperature cuben. It is essentially like a cuben fiber or DP Xpac product with a maximum operating temperature that approaches that of aluminum.

You could also consider inorganic materials. S-glass fabrics are occasionally available in weights below 2oz/yard (ACP sometimes has 1.4oz S-glass), and 2.6oz pure silica fabric is available from several sources. Woven basalt fabric is available from a company called Sudaglass at 3.6oz/yard. You could actually put any of these three fabrics INTO the fire without harming them. E-glass fabrics are available down to 0.5oz/yard, and would be plenty refractory for your application, too.

If you just want a barrier to the occasional spark, you could also just use light cotton or linen.

Edited by ckrusor on 05/05/2012 11:09:13 MDT.

That's just what I needed- thanks.
So I'll make the tent out of 30 denier 1.3oz silnylon, and when I get around to buying the stove, I'll worry about the curtain.

I guess I'll start another thread about my other questions.