Can I use gypsum or chalk that are not for brewing?

Hi,

The HB shops in my country don't hold any water treatment supplies, since this hobby is quite new here.

So... What are the alternatives ? these two salts are very common.

What kind of product should I look for?

thanks

I'm sure you can find it through chemical/science/lab supplies.

Gypsum is Calcium Sulfate - CaSO4

Chalk is Calcium Carbonate - CaCO3

Other common brewing salts should be easy to find

Sodium Chloride (NaCl) - Table Salt
Magnesium Sulfate (MgSO4) - Epsom Salt
Sodium Bicarbonate (NaHCO3) - Baking Soda

heh, I thought I was he only one who looked into this. I went to lowes to look for gypsum. Most products had chemical additives or were sold in large quantities. However I did find a product called Gold Bond Accelerator. It is used to quicken the set time of plaster. The ingredients listed are gypsum and quartz and it is sold in a 24 oz tub. The quartz content is <5% according to the MSDS.

The material safety data sheet says this about ingestion: "Ingestion: Gypsum is non-hazardous and no harmful effects are expected upon ingestion of small amounts. Larger amounts may cause abdominal discomfort or possible obstruction of the digestive tract. Seek medical attention if problems persist." The main risk is inhalation of quartz dust.

http://www.nationalgypsum.com/msds/msds01201.pdf

Two things to note:
When I added the gypsum to water most of it seemed to dissolve, but some of it would not dissolve, and settled to the bottom of the bucket.
This gypsum is light grey/tan, but some of the gypsum I have seen in LHBS is closer to light grey/white. Dont know if that means anything.

Another salt that is easy to get is epsom salt (MgSO4). You can get in a carton from a drug store. I got some from CVS that is ok for digestive use (as a laxative) in small quantities.