I have often seen the excellent micrographs of using Barker's reagent (2% HBF4) to anodize etch metallographically polished aluminium alloy samples.
I am specifically concerned with the extreme health risks associated with possible formation of HF, a well known deadly acid that should be treated with the utmost respect and calcium gluconate gel should be available incase there is skin contact.
To clarify, my lab does not allow such dangerous HF etchant to be used and hence I seek to confirm if Barker's is indeed much safer!
I am aware that strong HBF4 needs calcium gluconate gel (https://www.sigmaaldrich.com/GB/en/sds/sigald/207934 and https://www.ilo.org/dyn/icsc/showcard.display?p_version=2&p_card_id=1040), I believe this relates to the formation of HF through hydrolysis reaction (Article Hydrolysis of Fluoboric Acid in Aqueous Solution
).Yet, some MSDS for strong HBF4 do not stipulate the need for calcium gluconate gel (https://www.fishersci.com/store/msds?partNumber=A188500&productDescription=FLUOBORIC+AC+48-50%25+P+500ML&vendorId=VN00033897&countryCode=US&language=en).
While MSDS specifically for Barker's also does not raise any need for calcium gluconate gel in the event of skin contact (http://nebula.wsimg.com/845f81c1a8e5c887672140d4378de4b6?AccessKeyId=628C908180FB63374807&disposition=0&alloworigin=1).
If anyone can clarify my safety concerns with Barker's and may lead me to the appropriate safety literature, I would be incredibly grateful!
Best regards,
Gary
Dear Dr Gary,
Barker's reagent is widely used in revealing grain structure of Al alloys under polarized light. I have used it several times. Yes, it is categorized as hazardous chemical, but I don't think you need to panic before using it. Like handling other chemical reagents, you need to take standard precautions (e.g., wearing hand gloves, protecting glass etc.).
For more details, you can go through safety data sheet for fluoboric acid @ www.reagents.com.
Hope, you will feel confident about using it...
Thanks Chandan Mondal !
Through scouring MSDS documents I was coming to this conclusion of reasonably standard safety, and that with such dilute HBF4 the presence of HF is not an issue.
In your experience with Barker's, I take it that you've never needed calcium gluconate gel as a precaution?
My deep search into safety is to satisfy the strict standards of my manger... as well as making sure I am not putting myself or others into harms way of course.
Yes, Dr Gary.... my own experience with the reagent is rather satisfactory, both in terms of its effectiveness and safety. At the beginning even we used to keep gluconate gel, but never used it.
Of course, it does not mean that you can take it for granted. There is no replacement of safety precautions and awareness. Be alert and use it confidently.
thank you.
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