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Paper 101


I've read a number of paper patching posts and sites over the years, and Matthews "The Paper Jacket", and I would like to offer some info to paper patcher users. I used to work in the paper manufacturing business (actually I sold process chemicals to paper machines) for nearly 25 years. My expertise was optimizing the wet end chemistry of paper machines for maximum retention of solids (fiber and filler) and soluble (sizing, strength additives) material to achieve customer specs of paper for paper making companies. I have a BS in Paper Science and Engineering (now retired, but going back to school to be a dental hygenist. Why? I'm tired of overnight travel, and I wanted to do something different.)

I hope these comments can help the reader think out some issues, to assist in loading.

Paper is made from a suspension of wood fiber and water. The fibers run in length from "long" (for a soft wood fiber, which is added for sheet strength-sort of like re-bar for concrete), to "medium" (hardwood fiber) to "short" (ground wood fiber for newsprint/directory/coated groundwood magazine paper), to "very short" (called "fines" which are less than 76 micron). Too much long fiber makes paper with lousy formation (blotchy). This has poor printing and production properties (poor couch vacuum respones, poor printing, poor smoothness, and expensive (softwood kraft is expensive).

Depending on the type of paper being made, fiber lengths are blended to give enough strength, and good runnability on the machine, with desired end physical properties of paper (tensile, tear, burst, porosity, Hercules ink test/sizing, optical properites such as brightness and opacity and others). Fiber by itself, no matter what the length distribution is, can't do it all by itself for printing grades. Because of this, other additives are put into the mix. For increasing opacity and brightness, various fillers are added-such as calcium carbonate (CaC03, precipitated CaCO3>"pcc" or ground CaCO3>"gcc", titanium dioxide (tio2), clay (for acid pH machines), various chemical optical/fluorescent whiteners/brighteners additives (oba or fwa this gives you the "96" or higher blue white bright paper, and glows in a blue light presence). PCC and GCC are cheaper than fiber, so the papermaker tries to use as much as possible to reduce fiber costs (but also causes loss of strength), while maintaining the balance / compromise to machine runnablitily, and final physical/optical properties. For printing grades, it is common to have inorganic filler levels (pcc, gcc, tio2 or combinations of them, or clay-in acid/neutral systems) in the 20-26+% range in the base sheet.

Fillers are abrasive. Tio2 is very abrasive. Clay is very abrasive. The lighter the basis weight the sheet of paper is, a higher level of inorganic fillers are added (and weaker the sheet), so as to maintain opacity (ie "onion skin" writing paper). Keep this in mind when you shoot a paper patched bullet.

Other chemicals are added to the base sheet of the the paper to give printing properties. One is "sizing". In alkaline papermaking, which is the majority of the paper mills, usually AKD or ASA sizing is used to the basxe sheet ("internal" sizing). These chemicals by themselves don't impact any negative issues to rifle bores, but they do create an issue for wrapping a bullet. The more a sheet of paper is sized, the more water resistant it is. It takes longer to have a paper patch "get soft" or "weak" for wrapping. You can do quick test to see how much sizing the sheet of paper has you are using if you simply lick on spot on one side of the paper. See how long it takes to show a wet spot on the other side. Count the time in seconds. This will give you a good idea of the amount of sizing. Consider two sheets of paper: your local newspaper (which is unsized, or at most, minimally sized), and a sheet of writing paper, or onion skin (heavily sized). If you lick the newsprint, it will "show through" a wet spot almost immediately. If you do it to writing paper, it can take 10-60-100's of seconds, depending on the grade of paper. Sizing (base sheet, or "internal sizing") is used to make paper more printable at the presses for sharp images.

Low or unsized sheets have a capillary effect or "feathering" when supjected to inks. Highly sized sheets have crisp images, with limited feathering. Try this with your newsprint and fine writing paper. Use a felt tip or fountain pen on the newsprint, and then on the writing paper. The newsprint will have a high degree of "feathering." Sizing is sometimes added to the dry paper called "surface sizing" as well. So, a sheet of paper can be very water resistant (not water proof, or strong like paper towels, which use wet strength resins to retain fiber strength when wet, ie "Bounty" paper towels holding a cup of coffee at "Rosie's Diner" (if you are old enought to remember those tv commericials).

If you want to wrap a bullet, you can add some baking soda to your wetting solution. Baking soda will raise the pH of the water (more alkaline, or basic), and penetrate the highly sized sheet faster, to allow the fibers to get some water. You can also use warm/hot water (with or without the baking soda), as heat speeds all chemical reactions. You may also be able to "wet out" highly sized sheet of paper using vineger (which is acetic acid, and make it work even faster by using heated vinegar). I don't recommend it for paper patchers, as the acidic residue can lead to corrosion. Stay with the much safer (no corrosion issues) alkaline/basic higher pH (>7.0) such as baking soda and water. Try ~ half teaspoon (amount not critcal) of baking soda in a pyrex dish (about 2-3 oz) and fully dissolve (hot water will help dissolve it faster too).

Paper is also treated with internal and external starch to provide sheet strength. Starch is cheaper than fiber. Paper makers want to reduce the long costly strong fiber as much as possible. Starch gives the sheet "rattle." You notice this in onion skin. Hold one sheet of onion skin and shake it. A sheet with a high level of starch will have a rattle noise to it. That's because it is stiff, like adding starch to a shirt.

Starch can be abrasive to a rifle bore. Not much, but some. Starch by itself doesn't provide sizing, but it aids in retaining sizing to the sheet. So, if you have a lightweight, highly sized sheet, it likely has a fair amount of starch. It contributes to the wettability of the patch, and the abasion to the bore. Starch on the patch, may lead to some of the bore deposits sometimes mentioned. ( side note: Also, if some people use egg white as a protein binder to hold/glue a patch together, this can be a compliment source for those hard brown deposits in the bore.)

Paper has various physical properties (ie strength). Probably the most important to paper patchers is "tear." A paper machine squirts out a watery mix of fiber and additives at ~ 0.5-1.0% solids at the headbox slice. The "slice" (orifice from which the fibrous mixture exit) is about 1/4" or so wide, by as wide as the machine (8 ft to over 24 feet long). It squirts onto a revolving "conveyor belt" called a "wire." The wire is a continous belt, made of plastic mesh. I am simplifying the description a great deal but it looks like a highly woven window screen. The velocity of the wire is ususally just a tad faster than the linear velocity of the exiting jet stream of fiber from the slice. This differential is called "drag". It aligns the long fiber a bit for machine directional strength (which is important for runnability and profits). If you have too much drag, you get too much machine direction (MD) tear resistance (strength) , and less cross machine (CD or CMD) strength. When the MD tear = CMD tear, this is called a "square sheet." This is not necessarily good or bad, it just is. It depends on if you need this property for customer specs or machine runnability (and usually it's a compromise between the two).

You can measure MD or CMD tear yourself. Take a sheet of paper and tear the sheet along one axies of the sheet (ie along the 11' axis of the sheet of paper, then 90 degree along the 8.5" axis of the paper). If the fibers are aligned in the major axis, due to the DRAG of the wire" slice velocity, the sheet will tear EASIER along the major or machine direction MD). If you turn the sheet 90 degrees, it will normall be harder to tear across the machine (CMD) direction. This is because you are trying to tear ACROSS the longer fibers that have been aligned slightly by the DRAG created between the linear velocity difference between the jet/slice velocity and the wire. If you try tearing a sheet in 90 degree directions, and don't notice much of a difference, this is likely due to the sheet "being square" for tear measurements (cross machine tear ~= machine tear). Nothing wrong with a "square sheet" for the papermaker, customer, or paper patcher. Just don't get frustrated in trying to find the "stronger direction." You aren't wrong, you just proved to yourself the sheet has a square tear. Wrap it, and shoot it.

With this knowledge, you can now wrap your bullets with a paper paper so that you get maximum strength in the wrapping direction (which is the machine direction, or the direction with the aligned fibers due to the DRAG). So, any sheet of paper you have, you can give a little tear, then turn 90 degrees, and measure the tear again to see which one is stronger/weaker. The WEAKER tear is the STRONGER tensile (or PULLING) force, which is the machine direction, which is the axis you want to wrap AROUND the bullet, or PERPENDICULAR to the bullets major axis. Get that? Read it again until you have it down.

You can also do a quick test by holding a piece of paper in the palm of your hand. The moisture and heat from your hand will cause the paper to curl. The paper will curl in the CROSS MACHINE direction (or , the direction with the least amount of long fiber aligned with it.) This will help you position paper before cutting on a template.

So, what does all this mean? Paper IS abrasive. It DOES carry up to 26+% inorganic filler. (don't use glossy coated paper, as that has even more filler in the surface applied coating-not useful for paper patching. It's too thick, too brittle, and too abrasive). It DOES have water resistance (sizing), so learn to handle it (hot water or baking soda to increase pH).

I'm doing some investigating. In my opinion, the best paper may NOT be tracing paper or onion skin. It has a lot of sizing. Tracing paper doesn't have the filler, which is a GOOD thing. You don't want opacity in tracing paper.

LENS PAPER may be good, if I can find a source which is thick enough. Think about it, you don't want abrasives in lens paper to damage expensive optical lenses. You want it to be strong, and have some to minimal water resistance.

If you can't find a good source of lens paper, stick with .002-.003" tracing paper (to double wrap a bullet, to get ~ 0.08-0.010" total thickness/added diameter.

Your homework:
Bring a micrometer to the paper store and measure the thickness of the paper.

Class is now dismissed.

Go have fun during recess.

I have used the finer paper that you get at the Ritz Carlton hotels, but my supply ran and I haven't be able to stay at the Ritz for 15 years.  Thats what retirement will do to you.

Why buy them when you can make them yourself?

Jerry

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