The "crystal salt" is Alum as I understand it, which is a potassium aluminium sulphate, and the ingredient in most commercial antiperspirants is aluminium chlorohydrate. I am no chemist, but perhaps the idea is that Al is less mobile when bonded to a sulphate (where's our resident chemist Resinguy, I am sure he knows), either way, both contain aluminium.
McRob,
There can be aluminum in Alum - but there does not need to be. The company claims it to be Aluminum free. They could use Chromium or something else.
"Double sulfates with the general formula A2SO4·B2(SO4)3·24H2O, are known where A is a monovalent cation such as sodium, potassium, rubidium, cesium, or thallium(I), or a compound cation such as ammonium (NH4+), methylammonium (CH3NH3+), hydroxylammonium (HONH3+) or hydrazinium (N2H5+), B is a trivalent metal ion, such as aluminium, chromium, titanium, manganese, vanadium, iron (III), cobalt(III), gallium, molybdenum, indium, ruthenium, rhodium, or iridium.[1] The specific combinations of univalent cation, trivalent cation, and anion depends on the sizes of the ions. For example, unlike the other alkali metals the smallest one, lithium, does not form alums, and there is only one known sodium alum. In some cases, solid solutions of alums occur."
The Thai Chrystals that I use are made of Sodium and Potassium that are allowed to crystallize and then are shaped into a more user friendly application.
To say that 'both contain aluminum' is not correct in the sense that alum is not the same as 'up to 25% aluminum'.
Here is an explanaition of modern underarm deoderant:
"Solid antiperspirants are made with several ingredients, including wax, a liquid emollient and an active-ingredient compound. It's the active ingredient that gives antiperspirants their sweat-blocking power. All antiperspirants have an aluminum-based compound as their main ingredient. If you look at the back of an antiperspirant container, the aluminum-based compound is always the first ingredient listed. Here are a few of the common active ingredients:
* Aluminum chloride
* Aluminum zirconium tricholorohydrex glycine
* Aluminum chlorohydrate
* Aluminum hydroxybromide
The aluminum ions are taken into the cells that line the eccrine-gland ducts at the opening of the epidermis, the top layer of the skin, says dermatologist Dr. Eric Hanson of the University of North Carolina's Department of Dermatology. When the aluminum ions are drawn into the cells, water passes in with them. As more water flows in, the cells begin to swell, squeezing the ducts closed so that sweat can't get out.
Each cell can only draw in a certain amount of water, so eventually, the concentrations of water -- outside and inside the cells -- reach equilibrium. When this happens, the water inside the cell begins to pass back out of the cell through osmosis, and the cell's swelling goes down. This is why people have to re-apply antiperspirant. For those who suffer from excessive sweating, hyperhydrosis, aluminum chloride in high concentrations can prolong the swelling and may ultimately shrink the sweat gland, decreasing the amount of sweat it can produce.
An average over-the-counter antiperspirant might have an active-ingredient concentration of anywhere from 10 to 25 percent. The FDA requires that over-the-counter antiperspirants contain no more than 15 to 25 percent of the active ingredient, depending on what it is. The FDA also requires that all antiperspirants must decrease the average person's sweat by at least 20 percent. For those who have excessive underarm sweating, there are prescription products that contain concentrations higher than those of over-the-counter antiperspirants."
LINK
Here is what one manufacturer says about Alum and Aluminum:
"Our deodorant stones are made of potassium alum. It is a pure product made without the addition of chemicals, fragrances, oils or alcohol. The chemical formula for potassium alum is K2SO4Al2(SO4)324H20. Potassium alum is a colorless substance that forms octahedral or cubic crystals.
Bauxite is the ore from which alum is drawn. It is formed by the rapid weathering of granitic rocks in warm, humid climates and can be purified and converted directly into alum.
Potassium alum is soluble in seven times its weight of water at room temperature and is very soluble in hot water. When crystalline potassium alum is heated, some of the water of hydration becomes chemically separated, and the partly dehydrated salt dissolves in this water, so that the alum appears to melt at about 90 degrees C (approx. 392 degrees F), potassium alum swells up, loses all water, and becomes a basic salt called burn alum. Potassium alum has a density of 1.725.
Alum's are used for a variety of uses including as a powerful astringent.
If an aluminum compound, such as aluminum chlorohydrate or aluminum zirconium, which is very soluble, is used as an antiperspirant, that compound is readily absorbed. Once in the body, the aluminum portion of the molecule ionizes, forming free or radical aluminum (Al+++). This passes freely across cell membranes, and forms a physical plug, that when dissolved is selectively absorbed by the liver, kidney, brain, cartilage and bone marrow. ... Potassium alum molecules have a negative ionic charge, making it unable to pass through the cell wall. THEY ARE NOT ABSORBED. This is why our deodorants are safe to use and will not cause high levels of ALUMINUM in your system. ALUM and ALUMINUM are two different substances, with distinct chemical signatures. They possess different chemical properties which create different chemical attributes. "
TF
