Polyethylene v. Polypropylene

[Foolkiller]

I recently switched over (what a lovely ongoing task this has been) from all polypropylene bags to polyethylene bags... does anyone have a feeling about which is better -- while the polypropylene bags look clearer to me, the polyethylene bags I got from Bags unlimited with the acid free boards appear to not warp at all and the boards of higher quality...

 

what do you guys use generally -- obviously I use mylite2s and full backs for the expensive stuff... but just the generic books... what is everyone's preference?

[Zonker]

I have a strong preference for PE. PP is to my way of thinking too "crinkle-y." Also, the failure mode of PP does seem to involve wrinkling and warping, whereas PE's failure is moreso yellowing.

 

Having said all that, PP does seem to have won in the marketplace over the last 10-15 years, with Bags Unlimited being pretty much the only source for PE as far as I can tell.

[AussieRuss]

Hows this....

 

 

Why polyethylene rather than polyproylene?

 

 

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Many people have asked why Downtown Magazine sells only polyethylene sleeves rather than the cheaper polypropylene sleeves. In an attempt to answer the many inquiries we get, we offer the following responses.

Polyethylene is inert, translucent and creates a lower static charge than polypropylene, and those are the three main characteristics which make it a superior archival or storage material. An inert substance, according to chemists, is not readily reactive with other elements, in that it cannot produce other chemical compounds. In other words, molds, mildews, and discolorations will not occur with an inert substance, so there's no way a polyethylene sleeve can damage your collectible, nor can damage readily occur to it. Polypropylene is also inert, but that's where the similarities end.

 

The translucent nature of polyethylene prohibits a the greater amount of light than the transparent polypropylene. Light can be particularly harmful to collectibles, especially magazines, comics, books, photographs, artwork or any kind of cover or jacket that has color and/or photos or illustrations. By inhibiting the overall amount of harmful light that actaully makes its way to your collectible, the risk of fading is minimized.

 

The lower static charge produced by polyethylene as opposed to the higher charge emitted by polypropylene means that polyethylene will attract much less dirt, dust and other foreign, organic elements. And it is those elements which produce damage to collectibles.

 

Polyethylene is more flexible than polypropylene. By contrast, polypropylene is stiff and hard, while polyethylene is soft and pliable. The relatively rough surface of polypropylne has the potential to produce scratches to the surfaces of collectibles while the ptoential for scratching by polyethylene sleeves is minimal.

 

Many of the polypropylene sleeves are less than 2 mil. Many of the sleeves being sold on the internet and by hobby and comic shops are very flimsy and range from .5 mil to 2 mil. The majority of commercially-available polypropylene sleeves are 1 to 1.5 mil. Our polyethylene sleeves are 2 mil and 3 mil, respectively.

 

In more chemistry-speak, propylene (CH3CH:CH2) is is a sub-stratum of ethylene. Ethylene is the purest form of the base chemical and thus the purer better of the two. Consider this example: Suppose you were looking for the perfect gene to clone a tough guy. Now, would you rather have the genes from the son of a tough guy or fom the original tough guy, in this case, the son's father? Obviously, you want the purest tough guy genes, so you would go with the father. Polyethylene is like the father; polypropylene is like the son. See definitions below.

 

Due to its rigitity, polypropylene sleeves are more prone to tear, especially at the seams. Try this experiment if you don't believe this. Take an ordinary piece of writing paper (rigid) and a common paper towel (pliable). Try to gently tear each one. The paper tears readily, while you have to give the towel a little more of a tug to tear it. It actually kind of resists tearing by having some flexibility. The same principle applies for propylene vs. ethylene. The ethylene base provides more "give" and thus stronger seams and less likelyhood of tearing.

 

A good deal of polypropylene is imported. Much of it is imported from China, while our polyethylene sleeves are manufactured in the United States of America. There is one dealer who advertises "Made in the USA" who sells sleeves that say "Product of China" right on the package. I don't want to devolve into politics or have this become a discussion of global economics, so I'll just make the statement and let you decide which is more appropriate for you.

 

Polyethylene costs more. Simple logic dictates that it should be a superior product and it is. It costs more because it is a product of higher purity (100% Virgin) in addition to the advantages already presented, and will outlast and outperform any derivative product. Polyethylene provides better protection for both the short and long term.

 

[lizards2]

I prefer the poly e's because they don't wrinkle up. However, I buy whatever is cheap - poly e's seem to have had a real problem with sizing in the past couple years, in that silver age bags don't fit silver age boards, and the bag sizing is all smaller than the width indicated on the packaging - doesn't seem to matter what the brand. Poly p's don't seem to share this problem.

[Wally's Comics]

don't know about books

but polypropylene thermals

sure kept me warm in

sub zero temps...

 

 

 

 

[Ze-man]

 

what do you guys use generally -- obviously I use mylite2s and full backs for the expensive stuff... but just the generic books... what is everyone's preference?

 

Just spring for the Mylite 2's, you can afford it.

 

They will look better and you wont have to worry about them.

 

Ze-

[Sal]

i throw the generic books away.

[Mr. Zipper]

I have a strong preference for PE. PP is to my way of thinking too "crinkle-y." Also, the failure mode of PP does seem to involve wrinkling and warping, whereas PE's failure is moreso yellowing.

 

Having said all that, PP does seem to have won in the marketplace over the last 10-15 years, with Bags Unlimited being pretty much the only source for PE as far as I can tell.

 

Back when both types of bags were first introduced, PP was advertised to be more archival and have a longer life than PE.

 

PE is a much softer plastic. In laymans terms, I understand this to mean it has less stable oil content. PE turns yellow, can stick to each other and can get gummy under the tape.

 

PP, while it gets wavy, stays clear and doesn't get gummy. To me, this is a clear indicator this is a more stable plastic compound.

[krazy_kenny1]

The translucent nature of polyethylene prohibits a the greater amount of light than the transparent polypropylene. Light can be particularly harmful to collectibles, especially magazines, comics, books, photographs, artwork or any kind of cover or jacket that has color and/or photos or illustrations. By inhibiting the overall amount of harmful light that actaully makes its way to your collectible, the risk of fading is minimized.

I keep my comics in boxes where there is no light.

 

The lower static charge produced by polyethylene as opposed to the higher charge emitted by polypropylene means that polyethylene will attract much less dirt, dust and other foreign, organic elements. And it is those elements which produce damage to collectibles.

There's no dirt or dust in my boxes either, and, if there was, only the top of each comic is exposed, and, even then, they're all in BAGS.

 

Polyethylene is more flexible than polypropylene. By contrast, polypropylene is stiff and hard, while polyethylene is soft and pliable. The relatively rough surface of polypropylne has the potential to produce scratches to the surfaces of collectibles while the ptoential for scratching by polyethylene sleeves is minimal.

Has anyone ever scratched the cover of a comic by sliding it in and out of any type of bag? (tape doesn't count)

 

Many of the polypropylene sleeves are less than 2 mil. Many of the sleeves being sold on the internet and by hobby and comic shops are very flimsy and range from .5 mil to 2 mil. The majority of commercially-available polypropylene sleeves are 1 to 1.5 mil. Our polyethylene sleeves are 2 mil and 3 mil, respectively.

So?

 

In more chemistry-speak, propylene (CH3CH:CH2) is is a sub-stratum of ethylene. Ethylene is the purest form of the base chemical and thus the purer better of the two. Consider this example: Suppose you were looking for the perfect gene to clone a tough guy. Now, would you rather have the genes from the son of a tough guy or fom the original tough guy, in this case, the son's father? Obviously, you want the purest tough guy genes, so you would go with the father. Polyethylene is like the father; polypropylene is like the son. See definitions below.

I guess the concepts of progress and evolution are total BS then...Nazi

 

Due to its rigitity, polypropylene sleeves are more prone to tear, especially at the seams. Try this experiment if you don't believe this. Take an ordinary piece of writing paper (rigid) and a common paper towel (pliable). Try to gently tear each one. The paper tears readily, while you have to give the towel a little more of a tug to tear it. It actually kind of resists tearing by having some flexibility. The same principle applies for propylene vs. ethylene. The ethylene base provides more "give" and thus stronger seams and less likelyhood of tearing.

I don't go around purposely tearing my bags, so this point is moot. Besides, is it the end of the world if one of the bags I paid $3/100 for tears?

 

A good deal of polypropylene is imported. Much of it is imported from China, while our polyethylene sleeves are manufactured in the United States of America. There is one dealer who advertises "Made in the USA" who sells sleeves that say "Product of China" right on the package. I don't want to devolve into politics or have this become a discussion of global economics, so I'll just make the statement and let you decide which is more appropriate for you.

The cheaper one that doesn't turn the color of pee is more appropriate for me.

 

Polyethylene costs more. Simple logic dictates that it should be a superior product and it is.

 

 

 

Edit: BTW, this isn't a response to you AussieRuss...just whoever you copied this article from (thumbs u

[shadroch]

Its my understanding that the PP bags are superior.Perhaps I am brainwashed,but thats my understanding.

It doesn't matter to me as any book I deem a keeper goes in at least a myliteplus,and the rest go into whatever I have laying around. I can't remember the last time I bought any sort of polywhatever bag.

[davidpg]

Its my understanding that the PP bags are superior.Perhaps I am brainwashed,but thats my understanding.

It doesn't matter to me as any book I deem a keeper goes in at least a myliteplus,and the rest go into whatever I have laying around. I can't remember the last time I bought any sort of polywhatever bag.

 

Same here. I have tons of books still in both PE and PP that have been in them for at least 15 years and the books haven't been affected by the bags. The PP bags are overall better looking and seemed to have held up better than the PE bags (some of which are sticky...nothing to do with the Leather and Lace and Black Kiss comics contained within).

[Ringfinger]

Just to let you know, PET (Polyethylene Terepthalate) is Polyester which is Mylar.

 

Just a fun fact.

[Moondog]

Its my understanding that the PP bags are superior.Perhaps I am brainwashed,but thats my understanding.

It doesn't matter to me as any book I deem a keeper goes in at least a myliteplus,and the rest go into whatever I have laying around. I can't remember the last time I bought any sort of polywhatever bag.

 

Same here. I have tons of books still in both PE and PP that have been in them for at least 15 years and the books haven't been affected by the bags. The PP bags are overall better looking and seemed to have held up better than the PE bags (some of which are sticky...nothing to do with the Leather and Lace and Black Kiss comics contained within).

 

 

Before I sold my business to Diamond, I sold over 800 million plastic bags under the ComiCovers brand. Of the 800 million, 500 million were PE, the remainder PP. I've said this countless times over the years to collectors, retailers and archivists:

 

PE is no better than PP. PP is no better than PE. They are different plastics but they perform the same service. Polyester film (Mylar) is basically the same - but is superior to PP and PE because it's thicker (except if it's a Mylite - then it's really no better - sorry, Kenny!).

 

It's important to know that bags made of these materials do not protecting your paper collectibles from aging.

REPEAT: None of these bags are protecting your comic books from aging.

 

They are simply a means of protecting your comics from storage and handling damage. Storage and handling damage = bugs, rodents, water, handling, etc.

 

A cool, dark and dry environment will person_having_a_hard_time_understanding_my_point the aging process.

 

 

 

[Ze-man]

Those are indeed impressive numbers Gary, I guess what I would ask you is what do you store your personal collection in?

 

Not trying to be my normal overly smart alec self, just honestly curious.

 

Poly, or Mylar? Because my preference comes down to more aesthetics rather then preservation qualities even though I feel Mylar superior to poly hands down.

 

Ze-

 

 

[HOTFLIPS]

I have been selling PP for the past two years because there have been complaints about PE even before I got into this business. I personally have not seen PE turn but the reason i sell PP is because i have had no problems since I started selling them either. But, as the person said in the earlier post, mylar is your best option.

[Foolkiller]

I like both, and in some ways prefer PP... but some of the old yellowed bags that were PEs have some of the freshest whitest looking books in them when I've been digging in long boxes at stores.

 

Converting everything to mylar... I dunno -- doesn't seem worth it to me right now. I am starting to put anything that's super high grade into mylars.

[HOTFLIPS]

Yeah converting everything to mylar could be a bit pricey. ive heard different stories about changing PP or PE bags every 2 years or every 6 months or every 3 months. maybe thats the way to go if you feel its safer. maybe that is just a waste of money as well.

[lizards2]

I like both, and in some ways prefer PP... but some of the old yellowed bags that were PEs have some of the freshest whitest looking books in them when I've been digging in long boxes at stores.

 

Converting everything to mylar... I dunno -- doesn't seem worth it to me right now. I am starting to put anything that's super high grade into mylars.

 

Again, I think it's mostly the storage conditions - the books turn the bags yellow, not vice-a-versa. However...., if you have crapppy storage conditions, then both turn out ugly.

[Foolkiller]

I like both, and in some ways prefer PP... but some of the old yellowed bags that were PEs have some of the freshest whitest looking books in them when I've been digging in long boxes at stores.

 

Converting everything to mylar... I dunno -- doesn't seem worth it to me right now. I am starting to put anything that's super high grade into mylars.

 

Again, I think it's mostly the storage conditions - the books turn the bags yellow, not vice-a-versa. However...., if you have crapppy storage conditions, then both turn out ugly.

 

I wouldn't consider the storage conditions ideal -- but they are away from heat and light for the most part -- the temperature is probably around 70 degrees or so, slightly cooler in the winter... humidity is sort of a problem here but the comics are in a room that makes the dehumidifier not a great option. Haven't had any bags turning yellow yet, and some stuff I've had for over 15 years...

[marvelcollector]

Polyethylene or Polypropylene ?

 

The answer to that for a serious collector would be...Mylar.