Messages Archive

Subject:
not knowing anything ...
Response To:
cement rash ()

David Weaver
..about chemistry, and possibly misreading things, it appears that chromium is either in cement naturally or on purpose and at some point in manufacture or cure, some of it becomes hexavalent chromium.

the NIH has a bunch of studies where they found cement/concrete workers were sensitized to potassium dichromate.

https://journals.lww.com/dermatitis/Citation/2008/07000/Potassium_Dichromate.57.aspx

When I read about potassium dichromate initially, some of the references made it sound like "as an additive, it's used to slow the cure of cement", which would lead one to believe that cement should be orange. it sounds more like it's just there.

https://www.osha.gov/dsg/guidance/cement-guidance.html

(there's a reference at the bottom of this article about the origin of the chromium in the cement and possible ways to lower it).

As you mentioned that it's really breathing it that's the problem (and sanding off old finish was the first thing that came to mind - someone may sand those pieces in the future and suck it right in), maybe it's less of an immediate issue with cement because most exposure is to wet cement.

Interesting topic - I learned something from it, still point being that shellac is still a common finish in high end work. My separate experience is that if the person making the furniture is around, it's a very suitable top coat for most furniture items. repair of kid slobber marks and wet rings from sweating glasses was extremely quick. I certainly didn't use it for my kitchen cabinets, though - except to tone the wood under the top coat (crosslinked target 6000 series stuff).

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