???what causes the chemical reaction in self warming body lotions or face mask ???

i want to make my own at home and i want to know how to go about this and also where to buy all things needed. thank you for your real answers.???what causes the chemical reaction in self warming body lotions or face mask ???
I'm not exactly sure what you are wanting to make. I know of packs that if you press heat up. I will describe how they work.





They basically work by using a supersaturated solution of sodium acetate (CH3CHOONa). What happens is the solution is triggered to begin to crystallise the excess sodium acetate. Apparently they have some kind of metal hemisphere that creates some kind of sound wave that causes the crystallisation to occur. The crystallisation or precipitation is exothermic, that is creates heat.





Now, how to make one, first you need to get your hands on some sodium acetate, you could probably get it at a chemist, I'm not exactly sure where to find it. Once you get the sodium acetate you find the amount of water, basically the size of the heat pack, that you want to use. You then put the desired amount of water in something like a beaker


and add lots of sodium acetate. stir till it dissolves. Then, slowly heat up the solution whilst you keep stirring it, make sure that there is always some undissolved stuff at the bottom, if there isn't add more. I would say to get the solution to a temperature that is not boiling. Once the solution is hot enough keep stirring, making sure that there is still some solid at the bottom. After keeping the solution hot for a few minutes, pour the liquid into another beaker either using a filter or just by pouring off the liquid and keeping the solid in the original beaker. In the new beaker you will have a saturated solution of sodium acetate at a high temperature, to make it into a supersaturated solution, you have to gradually lower the temperature, leaving it outside would probably be good enough, once it is cooled down you have to treat it carefully, since it can crystallise easily, making it heat up before you want it. If you want to trigger its crystallisation you can just drop another crystal of sodium acetate in, and it will crystallise around that and get hot.





I suggest that after you have the hot solution you pour it into whatever casing you want it to be in, like maybe some plastic bag. The plastic would have to be thick and not melt at relatively high temperatures. If you let it cool down in that plastic bag (i suggest sealing it somehow as well) you can just bang the bag against something to make it crystallise (as long as you don't bang it so hard that it breaks the bag). The advantage of having it in that bag is that when you use the bag you can just put it in hot water again, and then once everything is dissolved, you can leave it out to cool down and become supersaturated again.





I hope this helps and is easily understandable.