Modified Platy = fuel saver?

I had an idea the other day about how I could modify one of my platys that just might save me some fuel. I am using alcohol for most of my cooking needs in the summer and to decrease the amount of fuel I use I thought I could preheat my water with the sun. I usually get in to camp and immediately try to get water so that the water will have a chance to warm up a bit before I try to heat it up with my stove.

Almost all of my hiking is at pretty high elevation and therefore my water sources tend to be quite cold. I think I could take a platy and darken one side with maybe a large black permanent marker (or something similar) and then set the water out in the sun to heat up for a bit prior to cooking. I still own one of the solar showers and they operate on the same idea. I've used the solar shower before to heat water when car camping and have been amazed with how hot the water will get with just setting it out on a sunny day.

I wouldn't be carrying any extra gear as I would just be carrying the same water container that I would normally have anyway.

Any comments or ideas on darkening one side of the platy?

-Skippy

It might be wise to experiment with the pen to be used on an old Platy. Water-based markers are likely to rub off. Solvent-based markers may weaken the water tank.

A quick and safe solution may be to carry an multi-purpose black trash bag. Lay the bag down first and place the Platypus on it.

CamperMom

My observation is that often the permanent black markers on plastic will easily rub off. If there is that white roughened surface for a label on them, the magic markers are much more permanent.

The plastic in the platypus may be different from what I have experienced, but trying it will give you the truth.

I might suggest Rustoleum Spray Paint for Plastics. You can read about the stuff directly at:
http://www.rustoleum.com/CBGProduct.asp?pid=118

Since it is formulated for plastics you have a plus going for you.

The minus might be that it was formulated for rigid plastics like outdoor furniture, and not formulated for highly flexed plastics such as the thin walls of the platypus. You might be lucky enough to find a technical suppport number or email on the Rustoleum site and get an answer to your question.

You might be able to limit the flexing by wrapping the platypus around something round that you normally carry. That you do carry something like this seems unlikely, however. Well, maybe wrapped around a stuff sack of some kind and secured with some useful elastic thing.

Nice thinking!

Let us know what works and what doesn't. Sounds like something I might like to have.

My problem with this idea is a couplefold - I also hike in places where the water is cold.

First is I find my water warms up better in a platy that is against my back, and the warmth from me is a bit faster than trying to warm up water lashed awkwardly on the outside of my pack in the sun.

The second is that if the point of carrying less fuel, I'm thinking I'll cary the extra 1/8 oz of fuel per boil to heat up the cold water I boil, than try to walk with an extra two pounds of water while it warms up.

Now it's a nice idea if you're lazing around in camp, and have time to leave the container out in the sun. but of course you can't really count on the sun being there either.

Phat,

Reread my post. I said absolutely nothing about carrying the water. My post was about after I get in to camp. I would not carry pounds of extra water to save fuel. Only a moron would do that.

Let me explain again. I would get into camp and first thing would fill my platy and lay it out in the sun (if there is any). Even if there is no sun, just by getting the water early you are allowing the temperature to rise (if it is not frigid air temp wise).

-Skippy

I thought about this as well but decided against it as I would prefer not to carry anything else to make it work. I am sure your idea would work and would probably be worthwhile if you carried a black trashbag as a pack liner thereby making it a nice multi use piece of gear.

Thanks,

Skippy

Carry something you use in camp regularly in a black stuff sack. When you remove the camp stuff for camp, then the black stuff sack is available as a black underlay for the water bag heater.

Maybe we're trying too hard.

If you use a foil windscreen you could shape it around your platy and lay it on the ground till it warms up. I don't know if this would be as effective as painting the other side black.

I tried my marker method as far as darkening the platy goes and the platy ended up looking pretty dang good. The ink seems to have adhered to the plastic very well. I am going to try it out (if it will stop snowing) to see how well it works compared to an unmarkerized (cool new word) platy.

-Skippy

I had one of those 12 ounce shower things, too, and if I recall, the black surface is on the inside of the bag, so that when it absorbs the solar energy, the water is heated. If you put black on the outside of the bag, when it absorbs the heat from the sun, the air will siphon it off. I think.

I tried out my darkened Platy for 1 hour in the sun (part of the hour ended up in the shade as I wasn't paying attention) versus a regular Platy. My starting water temperature was 57 degrees and I used 750 ml/25 oz of water.

They were laid out right next to each other and after the hour was up the darkened one had a water temp of just under 100 degrees and the regular one had a temp of 82 degrees.

On a nice day I could use the water to clean up with and for saving some fuel when cooking. Yes you can't count on a sunny day but it is a nice benefit when it happens.

-Skippy

You don't even have to darken your platypus. Simply fill with water, and place it in the sun over a piece of metal, say aluminum foil. This is basically a means of water purification touted in the third world as SODIS (solar disinfection). Water temps will get into the range needed to kill the bad stuff (160 degrees or so).

I haven't personally tired this, and I would imagine it works best when the bag is exposed at high noon, especially if placed at approximately a 30-40 degree angle. It would certainly save fuel.

What about purchasing one of Platypus' colored containers. (I believe they make it for holding/preserving wine) This would give you a darker plastic that would maintain its color indefinately. I think you have a great idea and I am going to adopt it.

I think this idea (colored bottle)would warm the water faster than a clear bottle.
I've experimented at home with 1 quart gator aid bottles. Other things being equal, a bottle painted black will heat water (in the sun) faster than a clear bottle.

Nice Idea!
How is the marker holding up? Did it rub off on your other gear? What marker did you use?

I use my MSR Dromedary for this. It's already black. I carry it empty in my pack, and use it to tank up on water when I get into camp. If I camp early enough to leave it out in the sun for a while, the water gets about as hot as I can stand for washing up.