https://www.youtube.com/watch?v=Nqxjfp4Gi0k loving this. i kind of want to try making some of the 18°C stuff myself;

A #DIY make-at-home non-toxic Phase Change Material that can act as a thermal battery, like a cool pack. it stays at 18°C while it's going from frozen to solid or backwards. That means you only need to lower it to somewhere below 18°C to "charge" it for cooling.

This is a specific ratio of Sodium Sulfate + Table Salt (NaCl) plus something that turns it into a gel (optional but very recommended)

#PCM #chemistry #HeatWave

DIY Supermaterial Could Save You From Heatstroke: Salt based PCMs

YouTube

order placed ... what have i done ...

thanks to smaller amounts of the ingredients costing drastically much more, I will now have ... an amount ...

guess i'll offer some packs to my parents and maybe neighbours for roughly the price of the ingredients, then it won't be as silly

@timotimo Hi there! I am so glad to have found somebody from Germany attempting to reproduce this. It's all I can think about since I saw the video.

I'll be honest, I expected to find a DIY community around this, but I can't find anything. Either there is this one big caveat that he didn't talk about in the video or... It's too new? Seems weird.

Anyway, would you mind sharing what you ordered and your results? Once you have any, of course.

@Tillerino sure thing, I went with
"GOLDEN PEANUT Xanthan Gum Powder 1 kg" (since i need four teaspoons for every cup of the sulfate, this will last me for roughly the rest of my life), "Sodium Chloride NaCl – chem. – 1 kg" and "GLAUBER Salts 2.5kg Sodium Sulphate E514 Na2SO4 Water-Free Pharma Quality Nature" from the "dicleanshop" and "Pack of 12 Reusable Storage Bags, BPA-Free Reusable Freezer Bags" from "ideatech"

dicleanshop charges 5 euros for shipping for this order

needless to say the kilogram amounts are wildly out of whack, i'll have about 600 grams of the NaCl left, a boatload of the xanthan, and I'd have ingredients to fill many many more freezer bags than i bought.

this is already roughly 80 euros. i'll have to do some actual napkin math to figure out what the finished goop will cost per liter or gram, and how much filling per bag is good, then i'd know what a fair price for one bag would be.

i'll hopefully have the first pot made on the weekend

@Tillerino I may end up with serious egg on my face if it turns out there's a big caveat that makes this not nearly as good as NHIL suggests, but it'd be nothing like putting my life savings in JPEGs

@timotimo Whatever you learn from this will already be worth 80 bucks, I'm sure. There will be no egg.

Anyway, thanks for sharing, I'm excited to hear more.

@timotimo I did a small experiment yesterday with just a bit of sodium sulphate that I grabbed from the pharmacy.

Everything is very straight-forward, but Xanthan is not easy to work with. It will clump up very quickly and not dissolve any further. Somebody in the Patreon gave the following tip: Dissolve the Xanthan in a tiny bit of isopropyl alcohol before mixing it in. Supposedly that solves the whole issue.

@timotimo The result? There is definitely something there. I am ordering a larger quantity of sodium sulfate now :)

Something else I wanted to mention: This recipe is two parts sodium sulfate decahydrate and one part sodium chloride decahydrate on a molecular level. I love how works out so well in terms of cups.

Since he said in the video that you want to saturate the water with salt, I am guessing that it's two parts sodium sulfate decahydrate and one part fully saturated salt water.

@timotimo Sodium sulfate decahydrate is a well known PCM and this is what all the literature talks about - always _decahydrate_. You can find a ton of results when you search for exactly that term e.g. on google scholar. SSD has a melting point of 32C. Fully saturated salt water has a melting point of -19C. So I guess this is all that we're doing. Mixing those two to adjust the melting point and then stabilizing the mixture.

@Tillerino yeah, i think this is the concept of "Eutektikum", but i am lacking almost all the knowledge required to really understand the wikipedia article. Furthermore, the article Kältemischung, which covers many salt + water mixtures, mostly concerns itself with cooling down some water when you mix in the salt, and reaching the lowest temperatures possible ...

I actually wanted to get some isoprop the other day and found out i went to the wrong place entirely haha. I'm hoping intense whisking (with an electric kitchen mixer appliance) will do it for now, though i do want to get isoprop.

Still waiting for delivery of the powdery ingredients.

I have the silicone ziplock bags already and i've been using one with just regular tap water in it for cooling to evaluate how well the seal holds up. i haven't dared to put it between my back and the chair to see if it pops open ...

@timotimo I think the alcohol will be well worth it.

I think my bad first attempt didn't stabilize enough due to my Xanthan troubles. I could already feel a much weaker effect on the second cool->warm cycle.

I think getting a lot of ingredients is a good idea. I have no idea what I'm doing and there will probably be a few more learnings of this kind :D