[aleksa]

  does somebody know what chemical is used to color antifreeze ( ethylene and propylene glycol) in common blu color?

[eugenedakin]

Hello Aleska,

To my knowledge, there is no 'industry standard' chemical for colouring glycols.  I have used many dyes, but the suppliers keep the chemicals (and their formulations) closely guarded.

For what its worth, any major supplier of industrial chemicals would be able to provide you with some.

Sincerely,

Eugene

[aleksa]

Hello Aleska,

To my knowledge, there is no 'industry standard' chemical for colouring glycols.  I have used many dyes, but the suppliers keep the chemicals (and their formulations) closely guarded.

For what its worth, any major supplier of industrial chemicals would be able to provide you with some.

Thank you for your answer but i need some simple chemical available in most labs to color glycols. is it possible to have the same effect with for instance methilene blu or brom phenol blu?
Sincerely,

Eugene

[eugenedakin]

Hello Aleska,

Here are a few acid-base indicators that you could try:
Methyl Violet
Crystal Violet
Ethyl Violet
Thymol Blue

I do not suggest Bromothymol Blue, thymolphthalein, or other indicators with blue transition points above or near a pH of 7, as the corrosion inhibitors in the glycol increase the pH between 8 and 10 and your colour may not be blue for long.  Caution should also be exercised with pH indicators, as they may require methanol or ethanol to remain in solution, which should never be used in a heat tranfer system due to flammability issues.

I hope this helps,

Eugene