On Thu, 12 Dec 1996 22:44:41 -0500, Gary Roberts wrote:

>Here's a little tidbit from a paper conservation text I was reading 
today...
>
>In order of potency, least to most, these are the solvents recommended for
>removing adhesives from paper:
>
>heptane
>benzine
>toluene
>acetone
>ethyl alchohol
>
>Surprised me, but than I haven't had Chem for many many years.  Comments
>anyone?

I'm also surprised, for several reasons.

  First, "benzine" isn't a proper chemical name for a solvent.  It's a 
generic name for various sorts of petroleum distillates, except perhaps in 
some countries where it may be the name for a particular sort of solvent.  
Benzene is a chemical name for a solvent, but it's a serious carcinogen and 
isn't used in a non-industrial context any more.  Any chance the paper 
conservation text was non-US, where "benzine" might have an accepted 
meaning?

  Second, I'm not familiar with heptane being used as a solvent in 
woodworking or finishing, at least.  It is a well-defined, specific 
petroleum distillate, but I'm not sure how it ranks vs. our more familiar 
"mineral spirits" and "naptha".  My guess is that heptane is comparable to 
"naptha" and "benzine" is comparable to "mineral spirits" or Stoddard 
solvent.

  The progression to toluene and then acetone seems appropriate.  Methyl 
ethyl ketone might fit in somewhere there, as does lacquer thinner, which is 
a mix of the above.

  Third, and most peculiar, is the listing of ethyl alcohol as being the 
most potent of these solvents.  There are many things that are soluble in 
the other solvents that ethyl alcohol will completely ignore.  Moreover, I 
would expect that virtually anything that ethyl alcohol would dissolve would 
also be dissolved by acetone and/or toluene.  Perhaps ethanol was listed 
last because there are a small number of adhesives that are insoluble in the 
earlier solvents that are uniquely soluble in ethanol (or methanol), even 
though methanol is not a more "potent" solvent?  In wood refinishing, 
ethanol would be the first, not last, solvent to try, because shellac will 
dissolve in it while other more resistant finishes won't.

  Finally, I'm surprised because there is no listing for solvents such as 
water (necessary to dissolve dextrose glue [e.g., stamps] and hide glue), 
ethyl ether, trichloroethane, carbon tetrachloride, or high-tech 
possibilities such as liquefied CO2 under pressure.

-- Michael D. Sullivan, Bethesda, Md., USA
-- Email: mds@a..., avogadro@w...