So if I got some cotton, and mixed it with nitric and sulfuric acids…
Actually, I had a question about getting the paper off of the mats:
I’ve seen people make paper using DIY kits. They dip their screens in the solution and allow it to dry. When the paper is dry, they peel it off of the mat. At what point in the commercial paper-making process does the paper come off of the mat? After going through the rollers? Paper looks like it has the same texture on both sides. If a roller compresses the paper on the mat, wouldn’t the mat-side have a rougher texture? Does it have a rougher texture, and I just haven’t noticed? How does the paper get off of the mat? I imagine an large ‘conveyor belt’ where the dried paper is drawn up a ramp while the mat belt makes a one-eighty and goes back to pick up another coat.
In the article, the term “mat” refers to the pulp itself; the pulp is spread onto the screen and becomes a mat. I’ll leave it to the expert to answer your questions, but I’d speculate that the mat can be removed from the screen once it’s dried, and maybe the screen and mat go between rollers together at first.
I hope we can lure **Una ** in here to answer a few questions.
I was wondering about the old use of rags. I assume that was for the cotton content but I was wondering is she could provide more information on it.
Im from the Fox River Valley (between Lake Winnebago and Green Bay) a place that has quite a bit of paper making. Thilmany (now part of International paper) has co-located pulp and paper plants. On the south side of Kaukauna it USUALLY didn’t stink too bad, but once and a while - phew!. And if you left the area it took a while to re-acclimate.
I should point out that a lot of trees for paper is grown just like any other crop (e.g. corn), and the paper making isn’t destroying forests continueously.
My brother studied paper chemisty, but I don’t know a lot about it.
I worked in a paper mill as a kid some 50 years ago. It was a recycling plant that turned out a heavy brown product which, as I recall was used in making corrugated cardboard for boxes and other uses. I started on the vat where the recycled paper was mixed with water and turned into a slurry. This was like a giant mixer and was a pretty dangerous place to work. It’s been a long time, but I think the erntire machine was over 100’ long. The slurry was sprayed onto the conveyor and squeezed, dried and then trimmed until it exited the machine on to a roller. A finished roll was about 5-6’ wide and about the same height when it was cut (torn manually) and started on a new roller. I worked that end of the machine also. The stench was somewhat foul, but within a few minutes of arriving at work you didn’t notice it anymore. Of course when you went home each day you reeked of the odor and everyone else could smell it.
Great report, Ma’am.
Hey, she can be funny, sci-fi-y weird, and even a little grumpy at times, but when Una submits a report, it’s darn accurately researched. Even to the point of submitting drafts to others (no, not me) for review. Una, you should host a site of your own.
We now end the suck up looking (it’s not, really) post and return you to your regular sad lives.
The paper says “Bleaching typically uses some combination of chlorine, sodium hydroxide, and hydrogen peroxide as whitening agents or lignin removers. Pulp and paper mills used to be a significant source of chlorine, dioxin, and other hazardous emissions, so many have switched from pure chlorine to chlorine dioxide, and some have eliminated chlorine entirely.”
This statement is somewhat outdated, at least for mills in the U.S. No bleached kraft mill in the U.S. uses any elemental chlorine for pulp bleaching anymore, and few if any mills of any type use it for that purpose.
The reason the paper does not have the impression of the forming wire on one side is that it leaves the wire while it is still quite wet and is, from then on, pressed in various ways on both sides. Any pattern left by the wire quickly disappears.
Old rags are, indeed, used as a source of cotton fiber. In fact, old blue jeans are a prominent part of the fiber source for currency paper. Acid is not used to process the rags, however. Heat and some caustic are used in a mechanical agitator to break up the cloth into fibers useable for papermaking.
The paper says “Bleaching typically uses some combination of chlorine, sodium hydroxide, and hydrogen peroxide as whitening agents or lignin removers. Pulp and paper mills used to be a significant source of chlorine, dioxin, and other hazardous emissions, so many have switched from pure chlorine to chlorine dioxide, and some have eliminated chlorine entirely.”
This statement is somewhat outdated, at least for mills in the U.S. No bleached kraft mill in the U.S. uses any elemental chlorine for pulp bleaching anymore, and few if any mills of any type use it for that purpose.
The reason the paper does not have the impression of the forming wire on one side is that it leaves the wire while it is still quite wet and is, from then on, pressed in various ways on both sides. Any pattern left by the wire quickly disappears.
Old rags are, indeed, used as a source of cotton fiber. In fact, old blue jeans are a prominent part of the fiber source for currency paper. Acid is not used to process the rags, however. Heat and some caustic are used in a mechanical agitator to break up the cloth into fibers useable for papermaking.
I agree with other commenters that this is a well researched article. I just have one bit of updated information. The article says “Bleaching typically uses some combination of chlorine, sodium hydroxide, and hydrogen peroxide as whitening agents or lignin removers. Pulp and paper mills used to be a significant source of chlorine, dioxin, and other hazardous emissions, so many have switched from pure chlorine to chlorine dioxide, and some have eliminated chlorine entirely.”
This statement is somewhat outdated, at least for mills in the U.S. No bleached kraft mill in the U.S. uses any elemental chlorine for pulp bleaching anymore, and few if any mills of any type use it for that purpose.
The reason the paper does not have the impression of the forming wire on one side is that it leaves the wire while it is still quite wet and is, from then on, pressed in various ways on both sides. Any pattern left by the wire quickly disappears.
Old rags are, indeed, used as a source of cotton fiber. In fact, old blue jeans are a prominent part of the fiber source for currency paper. Acid is not used to process the rags, however. Heat and some caustic are used in a mechanical agitator to break up the cloth into fibers useable for papermaking.
My first day here and I see a post I have experience with
jpu1 is right, the web pattern is pressed out by various pressure rolls while the web is still quite wet (but dry enough to lift off of the webbing). Usually an air curtain lifts the web from the belt and into the rollers. The shmooshier it is the smoother the finish will be on the web side, usually the top comes out pretty smooth anyway. However, being shmooshy means the web is quite fragile, the dryer it is the faster the mill can run (even the shmooshy stuff runs pretty fast). So, drier web = faster runs = cheaper paper = more likely to be able to tell the difference between the web side and the finished side. eg. look at both sides of a kraft paper grocery sack, the inside is much coarser. It is basically the same for all paper, clay coatings aside, all paper has a coarse side and a smooth side. This is not important unless the paper is used for printing. Printing on the web side tends to get a little fuzzy, which again is not important unless printing in more than one color (using rosettes). I can go into more detail about that if anyone is interested, but the short story is, on a standard ream of bond paper, the label usually tells which side to print on with the best results and thus which side is the finished side and which is the web side. Good luck trying to figure it out yourself, it is almost impossible to see with the naked eye, not nearly as easy as a kraft sack.
And they said I’d never get anywhere working in a box plant.
jpu1 is right, the web pattern is pressed out by various pressure rolls while the web is still quite wet (but dry enough to lift off of the webbing). Usually an air curtain lifts the web from the belt and into the rollers. The shmooshier it is the smoother the finish will be on the web side, usually the top comes out pretty smooth anyway. However, being shmooshy means the web is quite fragile, the dryer it is the faster the mill can run (even the shmooshy stuff runs pretty fast). So, drier web = faster runs = cheaper paper = more likely to be able to tell the difference between the web side and the finished side. eg. look at both sides of a kraft paper grocery sack, the inside is much coarser. It is basically the same for all paper, clay coatings aside, all paper has a coarse side and a smooth side. This is not important unless the paper is used for printing. Printing on the web side tends to get a little fuzzy, which again is not important unless printing in more than one color (using rosettes). I can go into more detail about that if anyone is interested, but the short story is, on a standard ream of bond paper, the label usually tells which side to print on with the best results and thus which side is the finished side and which is the web side. Good luck trying to figure it out yourself, it is almost impossible to see with the naked eye, not nearly as easy as a kraft sack.
And they said I’d never get anywhere working in a box plant.
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Excellent report as usual, Una. Does anybody around here (members OR staff) really appreciate you guys enough? The SDSTAFF write some of the best stuff I have read on the 'net. Apart from the Master, of course…
I am curious about the watermark as well- it looks like a last-minute add to the finished paper? And does the watermarking process differ with different paper content (wood vs. cotton)?
