[CAL-HUNTER]

Has anyone tested black plastic vs. clear plastic for water yield in a solar still?
I live in a dry and hot area in So CAL and have had good success with clear plastic.

Many of you live in cooler climates.

Would additional heat and water yield be generated by using black plastic to cover the hole and condense the evaporating moisture?

Just curious.

CAL-HUNTER

[scorch]

Originally Posted by CAL-HUNTER

Has anyone tested black plastic vs. clear plastic for water yield in a solar still?
I live in a dry and hot area in So CAL and have had good success with clear plastic.

Many of you live in cooler climates.

Would additional heat and water yield be generated by using black plastic to cover the hole and condense the evaporating moisture?

Just curious.

CAL-HUNTER

While I can't answer yes or know I would think black would be better because it reflects less heat. However a better question is are solar stills worth the work?

[CAL-HUNTER]

However a better question is are solar stills worth the work?

scorch,

I'm not sure what part of this great big country that you live in (I checked your member profile and it said that you were in a closet somewhere ), but I live in an area that gets about 10" of rain annually in a great year.

Some of the places that I take my family camping, shooting, and for escapes from the rat race, have no visible or easily accessible water for miles and mile. There is no gas, AAA, phone service or people. When we are out there we cannot depend on anyone but ourselves in an emergency.

I would guess that where you are, finding water is not as big of an issue. Find it, purify it, and drink your fill.

Where we go you would have to "make" water. There is usually plenty of cactus around, and a solar still is a very easy way to extract its life sustaining fluids. A few well constructed and productive stills can produce a good mount of drinkable water. Many ignorant people have not survived the harsh environments where we go because they did not have the skills or calm head to see them through a tough time.

Back to the question at hand: black vs clear plastic

My 4th grade boy has to complete a science project this year. I might run this by he and his teacher and see if I share the results with the forum members in a few months.

CAL-HUNTER

[Mac]

Clear is best

Think of greenhouses for example.

Another example - a clear plastic water bottle - half of it gone - left in sun and the water will start to condense on the sides and top...

[kevin]

Originally Posted by Mac

Clear is best

Think of greenhouses for example.

Another example - a clear plastic water bottle - half of it gone - left in sun and the water will start to condense on the sides and top...

mac is right, clear is better.

[scorch]

Originally Posted by CAL-HUNTER

scorch,

I'm not sure what part of this great big country that you live in (I checked your member profile and it said that you were in a closet somewhere ), but I live in an area that gets about 10" of rain annually in a great year.

Some of the places that I take my family camping, shooting, and for escapes from the rat race, have no visible or easily accessible water for miles and mile. There is no gas, AAA, phone service or people. When we are out there we cannot depend on anyone but ourselves in an emergency.

I would guess that where you are, finding water is not as big of an issue. Find it, purify it, and drink your fill.

Where we go you would have to "make" water. There is usually plenty of cactus around, and a solar still is a very easy way to extract its life sustaining fluids. A few well constructed and productive stills can produce a good mount of drinkable water. Many ignorant people have not survived the harsh environments where we go because they did not have the skills or calm head to see them through a tough time.

Back to the question at hand: black vs clear plastic

My 4th grade boy has to complete a science project this year. I might run this by he and his teacher and see if I share the results with the forum members in a few months.

CAL-HUNTER

I gotta say lucky. I haven't seen rain in almost 7 months.

[Craig]

Hi Cal-Hunter. I recently took a survival course and one of the projects that we did was to make solar stills. Feel free to check out my post that goes into detail on the subject:

Got back from Survival School

To answer your question, I would say that unless you're lucky or highly skilled, the plastic needs to be clear. If not, it's very difficult to tell where the plastic is placed relative to your catch container. If you're off a little or miss your container, all effort is wasted. Also, the short wave radiation of the sun's rays penetrates the clear plastic better, and captures the long wave radiation in the still. Similar to the concept of a solar oven.

I too live in an area with very little annual rainfall. Water is of the utmost importance as you stated, but take a look at my post link above. It discusses the time, energy and water consumed in making a solar still vs. the water produced. The results are scary if you're in a desert environment and water is scarce. If you've never done a solar still before, give it a try some time and keep note of the time it takes you and the water you consume in the process. Come back 24 hours later and compare that to how much water the still provides. For my still, the water deficit was substantial.

I'm no expert and I don't mean to sound like a know-it-all, but for me, it was a valuable lesson to do this first-hand and see the pros and cons of a still. If you try and get a positve net water gain, I'd love to hear more about it and learn what you may have done differently than I.

[crazydave]

cant remember if I've mentioned this elsewhere here but I have somewhere. I read a few reports on this from military guys fed up with it being taught that anything will do, to make a still in the proper context then you need clear plastic as it creates the greenhouse effect trapping the heat by changing the frequency of the light once its through the plastic which makes it warmer and brighter. a non clear plastic still produces water so it better than nothing but doesnt constitute a still as what you are making is more of a condensation/dew trap. I know the theory of black will attract more heat which it will but that also means that condensation wont form properly on the back edge till it gets dark.

hope that made sense.

[CAL-HUNTER]

Thanks for all of the info guys. Your comments and experiences have been very informative. I knew that I came to the right spot!
CAL-HUNTER

[B52gundog]

Rather than start a new thread on solar stills... I did a quick and dirty solar still test for the experience and to see for myself what the results would be.

I took a 13" x 9" brownie pan and put a few handfuls of grass and weeds in it. I put a small plastic catch cup in the middle. I covered the pan with cling wrap plastic then used masking tape to keep a decent seal around the pan. then I put a small rock on the plastic so the condensed water can drip into the catch cup.

I'm in Florida, it was hot and sunny today. I set the still in the sun from 1:30pm til 5:30pm (4 hours). I had a little dilemma, the catch cup was kinda deep and the plastic touched parts of the cup's rim and some of the water ran down the outside of the cup.

In the end, I had 1 ounce of clean water in the catch cup. As I was emptying the pan, there was a bunch of water in it as well (half an ounce or so). I wrung out the vegetation and came up with another half an ounce of water. It was dirty, but could be drinkable if necessary. I probably could've gotten another half ounce if I really tried to get every drop. So, a full shot glass worth of water was extracted from nothing but vegetation in a small pan in about 4 hours time. I probably could've gotten more if I was more meticulous making the still and used tainted water or seawater instead of vegetation.

A solar still may not be very practical in a wilderness survival situation, but from an urban survival perspective I've heard a decent solar still setup could be relatively productive. I just watched a couple of internet videos and it seems reasonably do-able (to build, low cost, and little space).

Here's a few pics of my little experiment today: