Chemical Safety

From HoloWiki - A Holography FAQ

If you have a poisoning emergency, call 1-800-222-1222 in the US unless the victim has collapsed or is not breathing then call 911.

Basics

• Material Safety Data Sheets (MSDS) can be found very easily on the internet and also come with chemicals when you buy them. Read them. Reading a MSDS.
• Use safety glasses, gloves and an apron when mixing or handling chemicals especially strong acids or bases.
• Use dedicated containers for mixing and storing chemicals. Never use household containers that are put back in to normal everyday circulation.
• Label and if applicable date every container that has a chemical in it such that anyone else can easily identify it.
• Keep a First Aid kit close by and include a sterile eye wash bottle if possible. Better is to have an eye wash station available.
• Know how to mix your chemicals and add/mix them in the order described.
• Know how to discard your waste chemicals according to your local area.
• Never add water to acid. Always add acid to water. With strong acids like Sulfuric acid much heat is created and can boil causing an extreme splashing danger. Dilute strong acids by filling your container with water, place the container in an ice bath and stir while slowly adding the acid.
• Never work when feeling fatigued or rushed.

Safety Apparel

Goggles should be splash proof. A face mask can be worn for dangerous chemicals but must be worn with goggles. Rubber aprons are helpful for strong chemicals. Long rubber gloves will protect your hands and forearms.

For fume protection the best solution is to have a well ventelated work area. For extremely strong chemicals it may be necessary to use a respirator. Make sure the cartriges are rated for the fumes you are dealing with. (ie. Carbon for Organic solvents).

Most of the chemicals used for making holograms are safe in that you will smell them before you have suffered any damage (the threshold of detection is lower the the threshold of toxicity). For some very dangerous chemicals you can become posioned before you can smell the chemical (The threshold of toxicity is lower than the threshold of detection). For this latter class of chemicals the only solution is to have a source of external air brought into a face mask. Modern paint booths using cyanide kicked paints use a set up like this. It is only mentioned here for people who are using gasses for exotic film treatments.

Read the MSDS and choose the safety apparel accordingly.

List of hazardous chemicals used in holography

• Dichromate - Do not allow Dichromate bleaches to contact your skin. Can cause burns known as chrom holes and if inhaled can burn the nose etc.

Also there is a problem with hexavalent chromium, a carcinogen, from Dichromates,and Alodine etc used in metal coating industry getting into the ground water supply. In-situ remediation efforts can change it to trivalent chromium before disposal. One method easy enough for us in holography is to reduce the Cr(VI) to trivalent chromium with hydrogen sulfite in a low ph solution. The dichromate bleach solution generally is around ph 2.4 as given by mix formula. To Remediate the dichromate bleach solution or any chromate/dichromate solution as long as the ph is below 4 and best below 3 is to add sodium metabisulfite (metabisulfite Na2S2O5 is available at photography formulary etc) until the solution is green and then extra to be sure Na2S2O5 in water hydrolysis forms Sodium hydrogen sulfite (bisulfite) NaHSO3. The insoluble relative non-toxic chromium III hydroxide settles out as precipitate, if your willing to wait. So you can then pour off the solution and find a chemical dump etc for the precipitate. If you have a ph meter then by all means add some sodium bisulfate or sulfuric acid before hand to adjust the ph to below 3 to ensure reduction. But in the case of bleach it doesn't require this as the PH is already low. It is possible not all Cr(VI) will be reduced to Cr(III) using the acid reduction with sulfites method. With regard to the low concentration in bleach it worked quite well. Other methods of reducing using Fe(II) or Mn(II) were discussed as a remediation effort. Here is a reference to chromium chemistry including using zinc to reduce Cr(VI) to Cr(III) : Cromium Reduction