Jeremy Taylor wrote:
> The biggest problem with phosphoric acid is it's low vapor pressure at room
> temperature,i.e. when heated it evaporates, vaporizes very readily. (faster
> than water) This result in more irritating fumes than most other etches,
> and is probably the reason very few people use it as such.
>
I always thought a substance of low vapor pressure would
evaporate less than a substance of high vapor pressure. I can
tell you concentrated phosphoric acid (80% wt) at room temp is
orderless, even when taking a sniff from the bottle. The stuff is
concentrated by evaporation so I don't know it can evaporate
faster than water. Its also not extremely dangerous to spill on
you. As a comparison I would say NaOH is a lot more corrosive you
your skin than con. H3P04. It takes a few minutes to start
feeling the pain, and I have sensitive skin.
Adam.