[Table of Contents] [Search]


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Methyl cellulose



             ***********************************************
           See footer at the bottom of this message (or top of
     the digest) for instructions on searching the archive, setting
                  your list options,and unsubscribing.
             ***********************************************

A few thoughts regarding the recent postings concerning Methyl
Cellulose.

First of all, it is always a good idea to check the archives of the list, as
many hints and suggestions can be found there.  I just did a search myself,
and it worked very well.  However, I did notice one thing lacking in
all the postings, and thought it might be prudent to clarify what we type of
MC we are talking about, what we're using it for, how we're preparing it.

Methyl Cellulose is a very general name for a range of cellulosic ethers
that have been "methylated", with added hydroxyl groups, which allows for
better water absorption, gel consistency and clarity.  Usually these are
varieties of hydroxypropyl methyl cellulose.  There is also hydroxypropyl
ethyl cellulose, commonly known as ethulose (which I have heard some use for
oil marbling), of which I think, Tylose is an example.

Dow manufactures a number of varieties under the brand name "Methocel" with
various grades such as A4M (not very clear, somewhat grainy consistency,
excellent for poulticing spines in book restoration, terrible for marbling),
E4M (clearer than A4M, still very viscous, used for spine poulticing,
adhesive additive, and could be used for marbling is thinned enough and
allowed to swell), etc.  These gels can only be dispersed in hot water, then
topped up with cold water and allowed to swell.  They are more commonly used
as adhesive additives in bookbinding, though some use them for marbling as
well.  If you buy "Methyl Cellulose" from a craft store, it would do you
well to learn more about what it is exactly: what grade it is, resulting
viscosity and centipoise (Cps).  Dow publishes an excellent technical
booklet on Methyl Cellulose which I highly recommend.  I got it for free
when I called 1-800-447-4369 (number is a few years old, but it may still
work).  They also sent me several jars of different grades to experiment
with.

MC used for marbling, is known as "cold water dispersible" methyl cellulose.
The Dow line begins with the letter J, and one example is j75ms-n.  This
doesn't require hot water, but uses a small amount of alkali such as calcium
hydroxide, or ammonia during preparation.  It requires a modestly higher pH
to swell, and will do so instantly.  You can also just let it sit, and keep
stirring it, but I find the resulting solution isn't as clear as when the
alkali is added (no to mention waiting for it).

This may be a point of interest to some who have criticized the problem of
PVA adhesives off-gassing acetic acid as it ages.  Would the addition of
calcium hydroxide in methyl cellulose, added to a PVA mixture help prevent
"vinegar syndrome" from occurring?  Some have suggested that adding alkali
may compromise the adhesive bond, but I have yet to find the cloth or
endsheets falling off of my books.  Others have suggested that it imparts
too much moisture and slow drying, resulting in increased board warping, but
I find that prevented if I make a stronger solution for mixing with PVA
adhesive, and use less of it.  The resulting "tack" is comparable to paste
and PVA mixtures, but without the lumps of paste, or potential aging
problems of that particular mixture.  Then again, I find it's all about the
application you are using it for, and what you find comfortable for your own
use.

If you are using methyl cellulose for marbling, cold water dispersible MC is
what works the best for size.  However you should adjust the solution to Ph7
before marbling, or the size will respond much the same way it does when the
water is too hard. , which was suggested by Peggy Skycraft in her
presentation on her experiments with various sizes at the International
Marbler's Gathering '92 in San Francisco.

Van Waters and Rogers also make a cold water dispersible product, which is
sold by some companies such as Daniel Smith for use as a sizing agent when
making paper.  I haven't been able to get more information about that
particular line, though it also works well in most cases as an adhesive
additive and poultice, and probably for marbling too.  My only observation
has been that it does seem to thin more rapidly after mixing.

As regards shelf life- in powdered form, it's nearly indefinite, but it
depends on storage conditions.  When mixed, distilled water is preferable to
deter thinning or "going off".  Much like paste, I use a clean implement to
retrieve it from the container, or just pour it out into my PVA mix.  The
variety you use will determine the working properties of the mix.  As a
result, using proportions such as 1:1 or 60/40, is meaningless unless you
know the grade specifications and initial percentage of the solution that
you have prepared in the first place.  There are other variables: An older,
thicker PVA may need a little more added than fresh PVA.  For sizing, it is
easily mixed to an exact percentage, and the vague "tack test" (rubbing and
blowing on sized fingers until it is sticky- used for parchment or gelatin
sizing to determine viscosity) isn't necessary.

So, I wonder what everyone is using, how they're preparing it, and if
they've found particular types more suitable for particular uses than
others.  Personally, I don't like A4M or plain "cellulose gum" at all.  It's
very grainy.  E4m seems much clearer, and F4m seems very similar to e4m.

For resizing after washing or external sizing of decorative papers such as
marbled papers, I prefer to use the cold water dispersible grades, as I find
it is less likely to leave shiny specks, which the hot water dispersible
grades can do in low concentrations (3-5%).  It seems to lend the paper less
stiff, so I generally use it at 5%.

For poulticing spines, the cheap stuff at the hardware store used for
wallpapering is fine, but avoid the "vinyl" paste.  Some types of instant
"wheat" paste contain methyl cellulose, and I think it's great when you have
a lot of paper and cloth linings , or old, dark, hide glue to remove.  I
still like a thin, clear MC poultice on my last application, so that I can
see what I'm doing, and avoid damaging the paper or sewing.  The alkali in
the cold water MC may help to swell the hide glue, and neutralize residual
acids, before applying new linings.

Jake Benson


Benson's Hand Bindery
Fine Custom Bookbinding & Conservation
Hand Marbled Papers
1319 B Summerville Ave.
Columbia S.C. 29201
Phone: 803.799.1853
jemiljan@worldnet.att.net
http://www.iprofsys.com/bensonsmarbles.htm

             ***********************************************
            BOOK_ARTS-L: The listserv for all the book arts.
      For subscription information, the Archive, and other related
            resources and links go to the Book_Arts-L FAQ at:
                      <http://www.philobiblon.com>

        To unsubscribe, type the following into the message body:
                            UNSUB Book_Arts-L
                        COMMAND MUST BE SENT TO:
                        LISTSERV@LISTSERV.SYR.EDU
             ***********************************************


[Subject index] [Index for current month] [Table of Contents] [Search]