Klucel

Mark Vine <100436.3447 [at] compuserve__com> writes

>I have received an enquiry from a book conservator without internet
>access regarding the use of Hydroxypropyl cellulose (also known as
>Klucel G or Klucel E) as a consolidant on a calf skin binding.
>
>The conservator wishes to apply Klucel G as a 4% solution in
>isopropyl alcohol but is hesitant as to the actual means of dilution
>in such a solvent. Can anyone with practical experience of using
>Klucel E or G provide some guidance.

Our experience of these cellulose esters is that they appear to work
well as consolidants for leather bindings. They are particularly
useful for treatment of reverse (rough) calf. Darkening of the skin
more controllable than with other media, such as paste. This is as a
result of the concentration of consolidant itself being more
controllable, but any medium at any concentration will change the
refractive index of a substrate, which usually results in darkening.

The technical information we received some years ago (perhaps 15) for
Klucel 'G' stated that the product could be diluted in either water
or alcohol. For the initial dissolving of the powder, water should
be used cold and alcohol hot. To speed the process, a magnetic
stirrer works well.  There are obvious attendant fire and inhalation
risks with alcohol, but use of appropriate lab equipment should
limit these to a acceptable level. Once dissolved the solution is
stored and used at room temperature. Curiously, if the product is
placed in hot water, or if an already mixed solution in water is
heated, the cellulose coagulates with an appearance a little like
egg white, this process reverses as temperature declines. We have
used both solvents and it is of course possible to mix them to
obtain, for example, a mixture of mainly klucel in water with a
proportion of alcohol to lower surface tension and enhance
penetration. The alcohol also acts as a preservative. We use Klucel
in alcohol on paper, where inks would be unstable in an aqueous
solution. In practice, if one has the time and patience, klucel will
gradually dissolve in solvents without agitation.

Klucel is said to be a very stable compound, but if the substrate is
acidic it must eventually be affected. It might to be advisable to
use one of the treatments for decaying leather before consolidating.
If the skin has been loaded with leather dressing, the penetration
will be reduced and could be patchy. This could result in uneven
colouration.

Mark Hingley
Conservation Section
Norfolk Record Office
Norwich
England


                                  ***
                  Conservation DistList Instance 16:37
                Distributed: Wednesday, December 4, 2002
                       Message Id: cdl-16-37-009
                                  ***