(The following information about backcoating and papercutters was written by Courtney Spooner, Cynthia Fulbright and Mette Pederson for distribution in the Backcoating class we teach together at the Origami USA conventions.)

What is Backcoating?
Backcoating is the combining of two sheets of paper back-to-back.  There are many different kinds of papers and combining methods, but each will produce the final result of two or more sheets of paper combined.
 

Unryu Paper
Unryu paper is tissue paper made from mulberry fibers. The mulberry fibers are very long and thus extremely sturdy for tissue paper.  It usually comes in a variety of colors (depending on the distributor). Unryu paper is usually imported from Japan or Thailand.  Each sheet is too thin to fold individually, so you'll need to combine two sheets.  Once the sheets are combined you'll be able to fold whatever.  The backcoated unryu works great for folding complex models and especially with wet folding.
 

Methyl Cellulose
Methyl cellulose is a great product for backcoating.  It's a totally inert so there are no adverse effects from using it.  It can be found in places that you might not expect, like in cough syrup as a thickener.  It also won't eat into any surfaces, so if you get it on your hands, clothes, baby, etc., no problem.  It washes right out with water.

Where to purchase Methyl Cellulose
If you want to purchase methyl cellulose don't call your local hobby and craft stores.  Most likely you won't be able to find it, although some large stores do carry it like New York Central Art Supply.  Your best bet is to look for it at a wallpaper store since methyl cellulose is also used as wallpaper paste.  But don't go in and just get any wallpaper paste.  Be sure you're getting methyl cellulose or some derivative thereof.  The product we use is ‘Methylan Cellulose’.  Since this product was slightly different from methyl cellulose, we called the company that produces the Methylan Cellulose to find out what the difference was.  One of their chemists told us the only thing different was that they had added a preservative.  This is great since with the Methylan Cellulose you can mix up a batch and store it for several weeks.  You  can make a cup or so at a time and save it in a Tupperware® container for a month or more.

Here's the address and phone number of New York Central Art Supply in case you happen to be in New York City:

 New York Central Art Supply
 130 East 12th Street
 New York City, NY 10003
 PH# (212) 477-0400
 http://www.nycentralart.com/

 Ross Adhesives
 Conross Corporation
 Detroit, MI 48209
 PH# (800) 387-5275

 (A box of four ounces only costs around $3.00 and makes 7 1/2 quarts.
 So, a single box should keep you busy for a while!)

Preparing the Methyl Cellulose
Ingredients:

• A bowl
• 1.5 cups of warm to hot water
• 2 teaspoons of methyl cellulose

 

A Surface to Work On
In order to combine the two sheets of paper, you'll need a hard surface to work on.  What we've found to be the best solution is a glass top coffee table.  You can use virtually any flat solid surface, though.  The MC will wipe up with a wet sponge, even after it's been dry for weeks.   Keep in mind there is a very small amount of MC compared to the water you added.  You can make lots of sheets on a glass coffee table before seeing much residue.  When we make a sheet, we let it dry while still on the surface.  If you have a lot of space you can make many sheets at once.  You could use your kitchen linoleum floor, plexiglas, hardwood floor, or a card table.  You could even use a large sheet of wood -- anywhere you have a hard free area.  You may find that plexiglas causes a smoother, shiny finish on the bottom side than glass.  We believe this is caused by the glass being more porous.  Keep in mind, if the surface has a texture, it might be picked up on the paper…which might be interesting if that’s what you want.  A word of caution, be careful of your surface if you’re using paper with darker dyes as they could stain some surfaces.
 

Applying the Metylan Cellulose
You'll need a soft paint brush to apply the MC.  Just a cheap 2-3 inch brush will do (ours cost $1.79). Lay the first piece of paper down flat on your newly selected surface.  When applying the MC, start in the center and work outward as you brush the MC over the first sheet.  You want to start in the center because when the paper gets wet it will expand.  If you start at the edges this expansion will result in wrinkles in the center of the sheet.  Apply enough until the sheet is completely saturated.  Then take your second sheet and place it flat on top of the first sheet as accurately as possible. If you don't get the two sheets exact don't worry; you can always trim off the outer 1/4 inch.  Or you can make a large sheet and cut it up into smaller squares so there's less waste.

With this second sheet on top, carefully brush the paper from the center to the edges. This removes bubbles from the sheets so they'll stick firmly.  You can get a plastic wallpaper smoother / bubble remover from your wallpaper store as well for around $3.  As you remove the bubbles you should notice the MC seeping into the top sheet too.  After the bubbles are removed apply some additional MC to the top sheet to ensure a good bond.  You really can't put too much MC on the papers, so don't worry about applying too much.  Over time you'll be able to gauge how much MC you'll need for different types of papers.
 

Drying the Sheets
Once you've combined the two sheets, there's not much to do until it dries.  If you let your paper dry while stuck to a surface you get several interesting effects.  Firstly, the top sheet may shrink more than the bottom sheet.  This is the way Yoshizawa makes his papers.  You have one sheet stretched more tightly than the other, this will produce a slight curling effect.  Secondly, if you leave the paper to dry on while stuck down, the paper won't wrinkle.  Some people take the paper up from the surface they pasted it on and let it dry somewhere else (on a laundry line for example).  Another benefit to letting the paper dry on a surface is that the side facing down on the card table, piece of glass, etc. will pick up the characteristics of that surface.  Glass will provide a silky smooth side, a vinyl card table will pass on its texture, etc.

If you leave a piece of paper to dry by itself, it will take a very long time to dry (like 2+ hours).  In order to cut this time down you can use a fan.  If you direct a breeze over the sheet it will dry in about 20 minutes instead of over two hours.  When the sheet is completely dry just pull it off the surface starting at one corner.  The paper is very sturdy now so it won’t tear easily.
 

Cleanup / Storage
Cleanup should be rather simple.  Use a wet cloth to wipe the surface you backcoated on.  You might have to wipe it several times, especially since the surface is now dry.  As soon as the MC residue hits water it starts to expand again.  But after a few wipes it should be all cleaned up.  You can store your MC in a Tupperware® container, zipper-lock bag, etc.  It should remain fresh for two months or so.  Again, if it has thickened during storage, just add a few drops of water until it returns to the correct consistency.
 

Additional Comments
You can also use MC for wet folding in place of water.  If you're planning on wet folding you might want to water your mixture down just a bit so thicker papers will absorb more of the moisture.

If you're interested in the unryu papers and can't find them in your area let us know.  We'll be glad to give you the name of our source in Raleigh, NC.  We have very competitive prices and a good selection.  Or, while you’re in NYC check out the New York Central Art Supply store (address/phone # above).  They have a great supply of papers including unryu.

You can also combine other types of paper using MC.  For example, combine two sheets of kami to have a thick duo paper.  Try using wrapping paper, office paper, your own handmade paper, etc.  One word to the wise though...do not try backcoating two sheets of foil paper. The MC never dries between two sheets of foil.  Mushagami, I guess!
 
 

We thought we  would let you know about the paper cutter we use.  We've had several people ask about them, including Origami USA, who now has one like ours.

We've had two types of paper cutters now. The first was one of the guillotine types, which can be pretty frustrating to use. A much better solution is a rotary cutter.  We use an industrial strength Saunders Rotatrim Mastercut Trimmer.  You can find these paper cutters in photographic supply catalogs.  They're definitely more expensive than regular paper cutters, but they're much more accurate and don't drag the paper like guillotine cutters do.  Overall, it is money well spent.   Over the last few years, other rotary cutters are now available, but they are not as heavy duty.

The Mastercut Trimmers use a circular blade encased in a housing that makes it almost impossible to cut yourself.  They're very safe, very accurate, and very sharp.

We ordered from Calumet Photographic is the company.  Their toll free number is (800) CALUMET or (800) 225-8638.  Call to have a catalog sent, and let them know you're interested in paper cutters (they have several catalogs).  They are listed under “Saunders” on the Item Index on the web site (http://www.calumetphoto.com/).

Here's the price list from the 1999 catalog:

Cut     Length Size     Price($)  Catalog #
12”     17.5”  x  15”    169.95    SO8912
15”     21.5”  x  15”    188.95    SO8915
17.5”  24”     x  15”    199.95    SO8917
24”     30.5”  x  15”    249.95    SO8924
30”     36.5”  x  15”    319.95    SO8930
36”     42.5”  x  15”    389.95    SO8936
42”     48.5”  x  15”    449.95    SO8942
54”     60.5”  x  15”    519.95    SO8954

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