>We have in our collection leather bridles, halters, reins, saddles,
>saddlebags and so forth that have a white "bloom," which I'm assuming is
>mold. It wipes clean, and I've used basic saddle soap which also removes
>the film.

What you have is called spue (or spew, if you like).  It looks like mold in
texture but is actually a result of excessive moisture in the air reacting
with a recent treatment of the leather.  (Biological examination under
microscopy will confirm this.)  Saddle soap is no good for this kind of
treatment, in fact, saddle soap can cause the problem.  To clean spue,
apply either denatured alcohol or mineral spirits.  A better treatment
would be Vulpex soap mixed with distilled watrer or mineral spirits.

Back in September we had the same problem in our saddle collection.  Our
HVAC system had problems right at the time of some unusually heavy rains.
We treated some saddles with the alcohol, and others with the mineral
spirits. The results were almost identical.  I like the alcohol because of
its quick evaporative quality.  It leaves no film nor residue.  In the
intervening 6 months we have had no reoccurrance of the problem.  (The HVAC
has been fixed, too.)

After cleaning off the spue, continue to monitor the environment.  In
closed micro environments, silica gel will help control excessive moisture.


If you determine mold present on leather, it can be treated thus:

Dry the storage enviroment with silica gel or isolate the objects into a
closed environment (poly bags) and use the silica gel inside the bag.
Monitor each environment with an RH strip.

After the mold dries, use a semi-stiff  brush in good ventilation to brush
off the mold.  White hair bristle brushes with flat ends work best.  These
don't hurt the leather, but will pick up the mold.  They're available from
Light Impressions, or most art or library suppliers.  It's a good idea to
also use a mask, vinyl gloves, and eye protection.

Treat the leather with ortho phenyl-phenol (OPP) to prevent spores from
regenerating.  Talus and Conservation Materials both carry OPP.  An
alternative is to swab the surface after brushing with denatured alcohol,
which will also prevent spores from reoccurring.   Continue to maintain a
proper RH environment.  The ideal humidity for leather is 50-55% with an
internal moisture content of 12-15%.  If ideal rh is maintained, the
moisture content will be pretty much automatic.

For more information on leather treatment, contact Paul Storch, Conservator
at the Minnesota Historical Society.  He's the best leather man in the
business, and has often taken the time to give me free advice over the
phone.  He has also done work on contract for us.  He's good.  His phone is
612/297-5774 or you can reach him at his private lab at 612/729-4449.

Good luck.
HBC

*****************************************
Henry B. Crawford        Curator of History
[log in to unmask]     Museum of Texas Tech University
806/742-2442           Box 43191
FAX 742-1136             Lubbock, TX  79409-3191
*********All opinions expressed are mine**********