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Cotton Armor

Cheap and practical ballistic armour.
  (+2, -4)
(+2, -4)
  [vote for,

Several months ago I found myself a flak jacket for $8 at yard sale. Naturally, I wear it to school every day, but I've been wanting to get some heavier armour sometime.

Obviously, finding a high threat level ballistic vest for $8 ain't gonna happen anytime soon, so I started looking into how armour is made and what properties are required.

Looking in wikipedia, I discovered that gangsters during the 1930s used heavily padded cotton vests to stop a good portion of the rounds used by law enforcement of the time (then they switched to the .357 magnum).

This of course, intrigued me, as cotton is cheap and easy to get a hold of, so I tried to do further research on the subject. Unfortunately, I had a hard time finding any definite sites onto them since I had no actual name for the vests.

Now, onto my idea. Back in the 1930s, ballistic armour was relatively unresearched for personal protection, so I figure with a couple of brains working together in modern times with knowledge of modern armour, something could be figured out.

I've read through the other ideas for armour and there's some really interesting ideas, but I'm wondering how effective a large cotton sheet can be at slowing down a bullet to less lethal levels. If you were to fold a large sheet very, very tightly and iron + sew the edges every couple of layers, what could it do towards slowing a bullet?

I imagine you'd have to do something along the lines of taking a king sized bed sheet and getting it down to the size of about a 9in by 6in pad (arbitrary numbers at this point), and then putting a couple of those pads on top of each other to achieve some sort of noteworthy effect, but maybe that could offer some ballistic protection.

Another theory is to apply some sort of resin to the cloth to give it added strength, but I was told that some resins heat up when cured, which could cause a majour problem with a highly compressed sheet of this manner.

Captain Xavious, Nov 06 2007

Wikipedia: Gambeson http://en.wikipedia.org/wiki/Gambeson
Mideval arrow-stopping coat. [jutta, Nov 06 2007]

A less cheap and less practical version The_20other_20Spiral_20Slug_20Stopper
[normzone, Nov 07 2007]

Mythbusters Episode 16 http://mythbustersresults.com/episode16
Bullets stopped by a book: Busted (although a 400-page hardcover did stop a .22 rifle shot.) [jutta, Nov 07 2007]

Bullet stopping stats http://1914-1918.in...dex.php/t56222.html
... and these are from a first world war .303 [xenzag, Nov 07 2007]

Modern Body Armor FAQ http://www.bodyarmo...body-armor-101.html
[jhomrighaus, Nov 07 2007]

Folded ballistic fabric patent http://patft.uspto....&Query=PN%2F4443506
The explanation given in the patent is incorrect. [ldischler, Nov 08 2007]

Kevlar 129 supplier http://www.infinity...nitydb.pl?catcarkev
[MisterQED, Nov 13 2007]


       Welcome to the bakery, Captain. I hope the shooting at your school subsides soon.
pertinax, Nov 06 2007

       What you're trying to build here is close what they used in the middle ages to stop arrows - I've added a link to the wikipedia entry on "Gambeson".   

       The main gotcha is that folding and quilting something is more effective than using the same amount of material without the layering. The thinner the individual threads, the better - so silk is better than cotton (but also more expensive, of course).   

       I see a lot of kids in fluffy padded jackets already. Maybe this could start a whole new fashion trend of lightweight ballistic armor in bright patterns...   

       This would make for a fun first year engineering exercise, a more explosive alternative to the good old egg drop experiment.
jutta, Nov 06 2007

       //If you were to fold a large sheet very, very tightly and iron + sew the edges every couple of layers, what could it do towards slowing a bullet?// nothing.
xenzag, Nov 06 2007

       I have to disagree. It's not an ideal approach, but anything a bullet has to pass through slows it's progress. Remember the Civil War stories of the pocket bibles stopping a bullet? Granted, bullets were a lot slower then.
normzone, Nov 07 2007

       Those Civil War stories would support your point better if they were repeatable..
jutta, Nov 07 2007

       A modern, high velocity weapon has a fearful capacity to pass through most domestic materials. I wouldn't want to hide behind a wall of books being fired on at close range. I have seen brick houses penetrated by bullets in my home town.
xenzag, Nov 07 2007

       I would not be willing to repeat the test. I have seen a .380 stopped by a phone book, but a .380 is hardly a significant caliber.   

       I like what they say about the even less significant .25 round.   

       "If you ever shoot me with a .25 - and I find out about it"...   

       The .22 long rifle is not to be sneered at, at velocities from 350 to 1,750 feet per second (Wikipedia).   

       I have seen .38 (not to be confused with .380) pass through a first wooden 2x4 and stop in the second.   

       All moot though. The first principle is to avoid gunfights. Somewhere further down the list is shooting from behind hard cover. Body armor doesn't even make my list, thank goodness.   

       I've fired a .303, [xenzag]. WWI regardless, that's an extremely serious round.
normzone, Nov 07 2007

       Take a hint from the samurai (who wore silk under their armor to help extract arrows).. Use silk instead. 1: lighter weight 2: thinner 3: stronger 4: shimmery/slippery feel really pimps out your flak vest.
bigattichouse, Nov 07 2007

       I had a buddy who was working at a company doing military contracts who was working on using multiple (100s) layers of garbage bag materials to stop bullets. I would think it would have issues with heat but the plastics are crazy strong and really thin. It doesn't have the pimp of silk, but it might be even cheaper than cotton.
MisterQED, Nov 07 2007

       Have you ever heard of Kevlar? Or any of its cousins? Cloth bullet proof vests are not even remotely uncommon. I would be willing to bet that most police officers you have met or in your town were wearing one. Cotton as a ballistic material is pretty lousy. Kelvar and its ilk are infinitely stronger than silk or cotton hence their use in Bullet proof vests and body armor. Even these advanced materials are not able to defend against modern firearms which is why the recent trend has moved toward light weight ceramics combined with ballistic textiles for modern military and police body armor.
jhomrighaus, Nov 07 2007

       I thinkI saw a Mythbusters where they put some "bulletproof glass" to the test. If I recall,it did well against everything except a high powered rifle. I like the idea of an engineering school challenge: make a bulletproof vest out of materials from the grocery store and fabric store. This sort of thing would make a good contest / personalities TV show, like the fashion design one.
bungston, Nov 07 2007

       I think there were some old-time fabric armors made with glue between layers. Wetting supposedly increases the strength of cotton.
baconbrain, Nov 07 2007

       I'm not sure that is the case. I suppose if its just some kid with a .22 revolver then you may be Ok but that same kid is just as likely to have access to much heavier hardware. Just a quick perusal of a wiki list of school shoots showed that 75% or more were committed with large caliber handguns(.357, 9mm) or with high power hunting rifles(30-30, .22 magnums, .308 etc) This being the case even the best body armor will be challeged to stop.
jhomrighaus, Nov 07 2007

       jared Diamond (Guns, Germs and Steel, chapter 3) describes how on Nov 16th 1532 Pizarro with 'a ragtag group of 168 Spanish soldiers' at Cajamarca, Peru, conquered Atahuallpa and his 80,000 followers equipped with maces, axes and slingshots. This massive army completely filled a valley for 15 or 20 miles. An estimated 7,000 native Americans were killed or wounded between morning and nightfall with the loss of only five Spaniards.   

       Diamond remarks that Atalhuallpa's troops wore only 'quilted armour'.
bhumphrys, Nov 07 2007

       Well, cotton isn't a half-bad idea. After all, "bulletproof" vests get damaged fairly often under heavy fire. Cotton is cheaper, and the users most likely won't be in war zones. If the users WILL be in war zones, they could afford to spend a bit extra.
Shadow Phoenix, Nov 07 2007

       I think maybe I was misunderstood in my reasoning for wearing my armour. :p   

       No school shootings have actually been done at my school, though there were a couple cases of guns being brought to a nearby school last year, and a (phony) bomb threat called in my school a couple years ago.   

       But my reason for wearing its that I simply like to wear body armour. :p   

       Found it for 8 bucks, I'm sure as heck gonna wear it. Though admittedly, the concern of school shootings is a rather real risk, but thats not really why I wear it.   

       Anyways, onto the relevant topic.   

       I realize that silk would be better, but my focus is on a cheap armour, and as already stated, silk isn't cheap. And yes, I know kevlar is a cloth, but that has no relevance on what I'm saying.   

       That idea of the garbage bags being layered heavily intrigues me, I'll have to look some more into that soon. The glued layers is a good thought too.   

       What I'm looking for is something to stop small arms fire, and if that one wiki article is accurate, the padded vests of way back when seemed to be pretty effective at stopping small arms fire, and its said they were made simply out of cotton and cloth padding. Also, I wouldn't expect it to be applied in high threat situations, but rather, I'd like to make it for myself and other individuals some time.   

       I just wish I knew more about the composition and arrangement of the padding for those mobsters' padded vests.   

       Another idea I had was for the implementation of the armour. Instead of having large, solid sections of the armour that would have to be completely replaced if just one part of it was compromised, why not make it in sections?   

       Just have pads of the armour, give it several attachment points on each side, and just strap the different pads onto each other. The anchor points would have to be inset a bit from the edges so that the pads would overlap when strapped together. If implemented like this, the armour could easily be custom fitted, damaged pads could cheaply and easily be replaced, added pads could be placed in vital areas to offer more protection where needed, and it'd be a lot cheaper to make.   

       Some flaws I see in this implementation is that explosives and projectiles coming from above or below would have a risk of getting through the sections, whatever is used to fasten the pads could have a risk of causing a ricochet, and the various straps and fasteners have a risk of pulling lose, wearing out, or breaking under heavy use. Considering this wouldn't be used for active combat though, I don't see those as major problems at the moment.   

       Should I make a new invention topic for this?   

       Anyways, thanks for all the responds so quickly!   

       One last thing, is that from what I read earlier in armour care and maintenance manuals, is that kevlar is considerably less effective when wet. Whether that's some property of just kevlar or shared with other cloth materials I don't know, but I feel I should mention it.
Captain Xavious, Nov 08 2007

       All materials will have pluses and minuses, I believe Kevlar is less effective when wet because the water lubricates the fibers as they slide across one another thus not dispersing energy as effectively. Any ballistic fabric works by distributing the force of the bullet over a wide area primarily through friction between the fibers in the weave. As I understand it a Kevlar vest will prevent the bullet from penetrating but does not prevent injury to the tissue. Rather than a puncture wound its like getting hit with a sledgehammer, bruises and broken bones being possible, but all more survivable than a gunshot.
jhomrighaus, Nov 08 2007

       That makes sense for why kevlar is less effective when wet. Wasn't really sure why, and that sounds as good as any reason. :p   

       And yes, stopping the bullet from puncturing you is not necessarily going to prevent damage, I realize that. In some cases the blunt force trauma is just as deadly as the bullet passing into you. I imagine it could even make things worse in some cases, as there's probably some instances where the organs get pulverized beyond effective repair, but yeah, it is typically more survivable than a bullet wound, I would think.   

       And thats where ceramic and metal plates come into place, usually covering the more vital organs, dispersing the remaining kinetic energy over the entire plate.   

       I'm thinking a cotton/cloth armour would definitely need some sort of BFT (blunt force trauma) plate in order to offer optimal protection, but, like many armours, the BFT plate is relatively independent from the rest of the armour.
Captain Xavious, Nov 08 2007

       Regarding quilted cotton: The stuff gets heavy. As a child, I had to sleep under a "comforter" that seemed to be made of layer upon layer upon layer of fabric. (I guessed that another layer was added when the outer one got frayed or dirty.) It wasn't a comfort to sleep under the damn thing, and I couldn't even pick it up to make the bed.   

       Small boat sailors wear multiple quilted sweatshirts for races. They get the shirts wet, and have a LOT more weight for hiking out to keep the boat balanced.
baconbrain, Nov 08 2007

       First I have to mention that the police frown on the public wearing body armor, especially if they happen to commit a crime and the level of that crime may change depending on the locality, so speeding may count and you might get into more trouble. So for this response I will assume that this is a theoretical discussion, because if it isn’t, go get a real vest or better LEAVE. Discretion is the better part of valor, or something like that.   

       First define your idea, what are your primary design specs: money, weight, wearability, and what the weapons you want to stop are. As mentioned by other subs each weapon has at least two different effects, blunt force trauma (baseball bat) and penetration (ice pick).   

       You seem to be hinting at creating a bullet proof vest which leads people to believe that it will stop modern weaponry (lots of penetration and a good bit of BFT), but then make references to an armors usefulness against ancient weaponry (usually had some penetration (arrows) or some BFT (mace), but rarely combined the two (lance)).   

       To stop penetration you need hard materials that will blunt an incoming object. To stop BFT, you need the combination of stiff materials and energy absorption, to both spread out the force and then absorb it, so that you don’t have to.   

       As for money, I feel sure that few here would refute the best anti-bang for the buck material is steel backed by any stiff pad. I personally can attest that a œ” piece of plate will stop pretty much anything and will in fact assault your attacker with reflected pieces of hot lead and copper. So if you are in a “Back to the Future” situation where you know you will be shot with a high powered weapon and have limited monetary resources, invest in a sizable piece of plate steel backed by energy absorbing foam.   

       If weight and wearability are the primary concerns, the answer is a modern bullet proof vest made of multiple layer tight weave Kevlar or Dyneema fabric with added plates of ceramic to blunt incoming penetrator rounds. Make sure that the vest is strapped tightly to the body as both materials are flexible and if hung loosely, they will just be carried into the body by the round. The tension of a tight wrap will effectively stiffen the system to spread the pressure out. A quick search found modern bullet proof vests are available on eBay for between $200 and $300. Making one yourself would be much more expensive.   

       If you want to stop a knife, I have heard that many bullet proof vests without plates fail due to the blade sliding between the weave. I don’t really understand this but that is what I have heard. So if you want to stop a knife on limited funds (and with unlimited time) I’d suggest making ring mail. The best has small riveted or welded rings but spring steel washers will stop lots of stuff. During a bout of unemployment I made ring mail out of stainless steel split washers in a four-in-to-one arrangement and it is impressive stuff that would allow only hypodermic needles thru the weave and I believe, though I have never tested, it would stop small arms fire (.22, etc.)   

       As for stopping a baseball bat, I’d suggest motocross gear which is mostly layers of hard plastic/metal plates over energy absorbing foam that will allow you to nearly laugh at your attacker. This is exactly what I would have worn to the battle with people who had maces, axes and slingshots, though the axes might give me pause.   

       The other thing you seemed to be hinting at is scale mail, made of overlapping scales of material attached flexibly to a support layer. Again here, steel works well, but scales have issues with blades that can slide up under the protection of the scales and individuals scales should be wrapped so they don’t rattle against other scales.
MisterQED, Nov 08 2007

       I actually do have a real flak vest, and I realize it's probably frowned upon to wear in public and for good reason too. Though I have looked up into this and it seems that it is perfectly legal (in the U.S.) to wear armour without need of permit or license, so long as you aren't a felon.   

       I understand your view of this and I appreciate that. If it really means anything, I would never consider using any armour to aid in commiting a crime (quite the opposite, really), but we'll just keep this theoretical in any case.   

       Design specs of my idea   

       First off, wearability is a pretty big concern, I have already thought about metal plating and I think that it really wouldn't be practical in the long run. It'd easily be able to prevent damage from a good amount of projectiles, but it would be extremly heavy, wouldn't be flexible, and it wouldn't breath at all. I'm a bit concerned with the weight of cotton layered heavily, but it would offer more flexibility and would probably breath a lot better.   

       Money is the next concern. Ultimately, I'd love to make a cheaper, lower threat level armour that could be afforded by small county police stations (very numerous around here) that have no armour whatsoever for the most part. Cotton would be nice because it'd be easy and cheap enough to be able to buy and replace multiple pads that have been used for testing purposes (finding the balance between weight and protection using metal could get pretty expensive with all the testing). Supposively, cotton has already been used to do what I describe, but I can't for the life of me found out the specifics.   

       Another problem with metal is the risk of ricochet. It means that the bullets aren't getting through the armour, but it also means it could go in any direction, and the chances of it actually going back to the shooter are relatively slim. You'd probably be just as likely to have the shot ricochet into an unarmoured part of you, like your head or legs.   

       As for what I'd like it to stop, its basically small arms fire from hand guns. Essentially, the same amount of protection my kevlar flak vest offers.   

       I've never made references to cloth/padded armour stopping medieval weapons or anything like that. I know that they have proven to help, I'm more concerned about how cotten was used to protect agaisnt bullets from the 1930s.   

       Also, one reason why kevlar is ineffective at stopping knives is that it relies on the bullets to expand upon impact to release a lot of the kinetic energy, a property that knives don't have. Still, it seems to me that it'd at least slow the knife down making it consderably more difficult, but I dunno.   

       As for the scale maille, I was just wondering if cotton armour (or kevlar/equivelants) would be as effective at protecting from firearms if it was implemented in seperate pads that could then be overlapped and assembled. Its not really scale maille persay, more like a modular armour that could easily be customized and repaired. I realize knives could easily get past the armour and it would have some vulnerabilities, but bulletproof vests aren't typically good against knives anyways. As for the rattling, I was referring to ballistic cloths being implemented this way rather than metal.
Captain Xavious, Nov 08 2007

       I don't need to buy my own, I already have armour. And I don't plan on getting rich off this, I just wanted to do as much research on this subject as I can. Just browsing the web I found this site, I figured it could really get some brainstorming done and I have already been enlightened and many ideas that I haven't thought of have been brought up.   

       I appreciate the many ideas and problems that have been brought up and I'd like to thank everyone for your words.
Captain Xavious, Nov 08 2007

       Cotton armor of this sort could also be manufactured in countries with land mine problems. Mine clearers could wear these suits. Currently I understand many have little or no protection.
bungston, Nov 08 2007

       There's another use that I haven't thought of before. Good idea.   

       I know that a cotton armour would never replace something like Kevlar and the ilk, but cotton is something that is available to pretty much everyone. It'd be an alternative that most countries have access to and can work with, but that itself could bring up many problems.   

       I wonder what is needed to stop explosive forces from harming you... hmm... definitely fragmentation protection and probably BFT protection as well, but not too sure after that...
Captain Xavious, Nov 08 2007

       for explosives the name of the game is deflection and absorption. Bomb squad suits have lots of padding with harder surfaces designed to deflect blast energy outward away from the critical parts of the body. The new military vehicles in Iraq designed to prevent IUD damage have V-shaped lower Hulls that deflect a blast out away from the passengers.
jhomrighaus, Nov 08 2007

       If an IUD damages you, it is already inside your V shaped hull. Special hulls might help against IEDs, though.
bungston, Nov 08 2007

       If an IUD penetrates your V-shaped hull, you need to change your gynecologist.
MaxwellBuchanan, Nov 08 2007

       Wikipedia and mythbusters are not sources of information.
Antegrity, Nov 09 2007

       //Wikipedia and Mythbusters are not sources of information//   

       I would disagree, both sources contain a weath of information, however the data user needs to be rigerous in their investigation practices and follow up on the sources cited where wiki is concerned. I have personally found many wiki articles to be quite accurate and consistent with other more traditional sources. As to mythbuster I find their experimental technique to be fairly rigorous however the focus is sometimes quite narrow. Depending on the type of information cited mythbusters(at least the US version) is quite good at actually performing a controlled set of experiments.   

       Is either the journal of natural sciences, of course not, but even such journals have been brought into question in recent years. For the type of information normally discussed on the HB both Wikipedia and Mythbusters are perfectly acceptable when cited appropriately.
jhomrighaus, Nov 09 2007

       Hear, hear, [jhom]! Wikipedia is an excellent starting point for hard research, and quite good enough for most pop culture information.
baconbrain, Nov 09 2007

       I just tore out my kitchen's ceramic floor and packed it in 3 mil garbage bags for disposal. The broken tiles are as sharp as broken glass and the bags held up well. I'd still bet they'd beat almost anything for cheap armor. I may just have to take a box and see if 166 sheets (.5") would stop a bullet. It would obviously be better if the layers were stuck together with some flexible glue so that the system could bend slowly to form to a body. But the plastic seems to really like to stick to itself anyway. I think that $20 box of bags could stop a lot of mine shrapnel too and you can't get much denim or canvas for $20.
MisterQED, Nov 11 2007

       Well, that'd be easy to test. Somebody fire a round into a box of garbage bags and see how far it penetrates. The bags should still be useful for dry garbage. I'd try it, but all I have is the wimpiest BB pistol ever made.
baconbrain, Nov 11 2007

       Somehow I would have to believe that with all the money in the world that is spent on armor and armor research(a sum of money that I doubt we can even properly comprehend) that someone has tried just about every material on the planet to determine its potential for use as armor.   

       Just a thought.
jhomrighaus, Nov 11 2007

       A good one, too.
baconbrain, Nov 11 2007

       Well that is true but I also know that Dyneema and garbage bags are both polyethylene. Now chemistry is not my forte, so that similarity may mean almost nothing, but I'm just wondering if some of the science that went into creating Dyneema made it to garbage bags then it might show promise. And remember we are not trying to find the best vest material, which is either Dyneema or Kevlar, but the cheapest. So maybe it will take .5" of Dyneema to stop a bullet and maybe it will take 2 or 3 times that in bag material, but since the bags are 100s of times cheaper, it has a shot. Also as I said in an earlier post, I had a buddy who worked at a company that was trying it for making armor, though I have no idea what plastic sheet they were trying. And never discount an idea because someone should have thought of it already as I am constantly amazed at what people don't think of.
MisterQED, Nov 12 2007

       diamond and charcoal are the same material as well, but......
jhomrighaus, Nov 12 2007

       Somewhat true,depnding on the definition of material, but Polyethelene sounds like it defines a type of bonding. My guess is the difference is more like graphite to nanotubes in that the length of the molecular chains gives the strength.
MisterQED, Nov 12 2007

       A combination of materials with different desired properties would be the best solution. If you have just bags, the bullet would still enter your body, wrapped in plastic. If you use just cotton, the bullet will tear through.   

       What you need is a way to spread the load over as wide an area as possible by having a stretchy layer that bonded in patches which can pull apart to spread the load. Behind that layer should be a compressible layer that gets pushed in and to the sides. This should be backed up by a non-flexible weave that will attempt to stop the bullet.
marklar, Nov 12 2007

       That is why I mentioned the glue layers. I imagined that it could work like rubber cement in that it would allow slow bending by allowing the layers to move independently in shear to conform to the body, but when a quick force is applied they would resist and act as a solid and spread the force out to a larger area.   

       Also from a quick wiki-search the difference between Dyneema which is UHMWPE (ultra-high molecular weight PE)and plastic in plastic bags HMWPE) is the length of the molecular chains and the alignment of the fibers. Dyneema tensile strength is around 350K psi vs. only 10K+ psi for plastic bags. So it's possible that 30+ times the thickness of plastic bag material would equal a thickness of Dyneema material. Not too bad since it is 100s of times cheaper. Anyone know how thick a Dyneema vest is?
MisterQED, Nov 12 2007

       Well if you don't mind looking like the michelan man then any number of materials would work quite well for your needs. On the other hand, walking around in a suit of garbage bag armor that weighs 300+ lbs just to save a few bucks seems kind of silly, and would tend to defeat the purpose.   

       If a ballistic fabric pad of 1/2 inch thickness is needed for a particular level of protection it would not seem reasonable to make a garbage bag suit 15 inches thick(for an overall thickness of more than 3 feet and width of over 4 feet you would not even be able to walk through a door way)   

       All of this would seem to defeat the first of your many design criteria.
jhomrighaus, Nov 12 2007

       After a quick search I found that you can get Kevlar 129 fabric for about $20 per sq.yd. If you want to stop a bullet to the minimum level II-A, to stop a FMJ 9mm, you need 16 layers of 129. So making the assumption that your chest is about 2 sq.ft. you should be able to make a vest for $160. 3/16" thick plus padding. Seems like a deal.
MisterQED, Nov 13 2007


       I had no idea Kevlar actually is that cheap. Now my question is, how easy is that to acquire? Because $160 for a custom built ballistic vest sounds like an awesome deal.   

       The idea of garbage bags really does intrigue me. Though as stated, it'd take 30+ times as much material to make it equivalent to Dyneema, so it definitely wouldn't be the only component for a cheap armour. Though I imagine if you use that as the outside material, it'd be given significantly superior protection from water and probably many chemicals while dong something towards slowing the bullet down a good portion. Sounds like it'd be a great component to this armour.   

       So some sort of adhesive between layers of cotton, combined with many layers of plastic garbage bags, also probably held together with some adhesive, and arranged them in such a way to complement each others' attributes, and you just might have something that can stop a bullet, given enough thickness.   

       This is something I want to try soon, might yield interesting results.
Captain Xavious, Nov 13 2007

       "In tonights top story a local man fatally wounds himself while testing what police describe as "homemade Body armor". The body was found surrounded by empty boxes of trash bags, old Tshirts and tubes of Rubber cement, police are still trying to understand what exactly the young man was thinking, in other news...."
jhomrighaus, Nov 13 2007

       Heh heh... I think I'd find a slightly better way to test it out. :P
Captain Xavious, Nov 13 2007

       [MisterQED] 1 sq.yd. = 9 sq.ft.
2 x 16 x 20 / 9 = $71.11

       If you use 18" square pieces, you would need exactly 4 yards = $80. Personally, I'd want to use 5 just to be sure.   

       Re: glue layers - I was thinking more along the lines of dipping each cotton layer in melted plastic and rolling it through a mangle so that the fibres are saturated.
marklar, Nov 13 2007

       I was worried someone would think I made a math error...but my vest has a front AND back, so 4 x 16 = 64 / 9 = 7.111 (or something) and then rounded up to 8 because the fabric is sold in 60" wide (rounded to two sq.yds. for $37.50). So you'd buy 4+ yds of fabric to get the material you needed. Also thes aren't knife proof vests. Any sufficiently pointy weapon will separate the weave and get to you. Best to back it wth some hard plastic (they suggest lexan) for puncture and BFT resistance. I'll put up the links I found, though Googling "Kevlar 129" with get them quicker.
MisterQED, Nov 13 2007

       After note on the garbage bag idea, it is possible that the material that my friend was testing is called Spectra Sheild which looks like regular plastic but isn't, as it is the latest greatest stuff. Basically it is two 90° layers of Spectra in a plastic format. Also Nylon beats silk and the best is to train a spider to weave you one because some spider silk beats everything.
MisterQED, Nov 13 2007

MaxwellBuchanan, Nov 14 2007


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