Is there much difference between PP and OPP for cel storage?
Is there much difference between PP and OPP for cel storage?
I saw someone talking about this somewhere else and it made me think if there is much of a difference or benefit from using polypropylene bags PP over OPP bags? A lot of my cels came in either of them and was just wondering if its fine to just keep them as is, thank you
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sensei
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Re: Is there much difference between PP and OPP for cel storage?
Most archival sources stock either polyprophylene (PP) or polyethylene (BOPP). Either is fine for cel storage. I don't recall seeing OPP (oriented polyprophylene) sold as such. It's probably OK also. Archival polyester (PET or Mylar) is also an option but it has the bad side-effect of storing static electricity and so (I've heard) it tends to stick to cel paint. It would be OK for sketch storage, however.
Overall, it's worth remembering that the cel itself is chemically active (or is prone to "intrinsic vice" as archivists say) and so it will damage the cel bag quicker than the cel bag will hurt the cel. That said, keeping a piece of MicroChamber paper in the same bag as the cel will sop up the fumes given off by the celluloid acetate and prolong the life of both the cel and the cel bag. I'm doing a full inspection of my cel collection, and I'm finding that bags protected by a sheet of MC paper are in much better shape 5 years after the last bag swap than most of the new cels that I receive from Japan. (One nice cel came in a dry-cleaner's bag cut and taped around the cel.)
Overall, it's worth remembering that the cel itself is chemically active (or is prone to "intrinsic vice" as archivists say) and so it will damage the cel bag quicker than the cel bag will hurt the cel. That said, keeping a piece of MicroChamber paper in the same bag as the cel will sop up the fumes given off by the celluloid acetate and prolong the life of both the cel and the cel bag. I'm doing a full inspection of my cel collection, and I'm finding that bags protected by a sheet of MC paper are in much better shape 5 years after the last bag swap than most of the new cels that I receive from Japan. (One nice cel came in a dry-cleaner's bag cut and taped around the cel.)
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oxypetalus
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Re: Is there much difference between PP and OPP for cel storage?
I've been using BOPP/OPP bags for at least a year and so far so good. The bags I bought were listed as "Acid and lignin free" and "Archival safe" so I was pretty confident they were safe for my cels/sketches. I believe the point of OPP or BOPP is that the way the plastic is made/cut produces a plastic film that is super transparent and crystal clear which I prefer. I tried a few random packs of PP bags in the past (I think they were marked for storing newspapers or magazines ?) and they were thicker and had a slight cloudiness to them compared to the BOPP/OPP bags I am using now. One thing I did notice though is that my BOPP bags are quite thin so I wonder if they will pucker/ripple in the back where they contact the paint faster than other bags. I'll have to wait and see how long they last.
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sensei
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Re: Is there much difference between PP and OPP for cel storage?
I agree with the "crystal clear" aspect of the BPP bags, which makes the cels more viewable, and I also agree that their thinnness also makes them more prone to pucker than PP. That's an issue with two sides, though: I find premature bag puckering to be a warning sign that the cel is becoming more chemically active and may need to be quarantined. So while PP bags last longer and don't pucker as fast, they may also conceal growing problems.
That said, I'm doing a complete physical inspection of my collection, some of which has been in my hands for 20 years. The part I'm working on was last rebagged in 2017. I slit my bags down two sides and store them in my Profolios with one slit side facing up toward the opening of the sleeve. And for some time I've put a half or whole sheet of MicroChamber paper in the cel bag, protected from the painted side with an extra plastic sheet (always BPP).
(For newcomers, MicroChamber paper is coated with a chemical surface that adsorbs and neutralizes acidic fumes, increasing the useful age of artwork on plastic, which has the bad habit of chemical instability aka "vinegar syndrome." It's not a cure, as VS arises from inside the plastic sheet, but it does effectively treat the earliest signs of it and so keeps it under control. It's readily available from several sources online; I buy mine in big sheets from Bags Unlimited and cut them to the needed sizes. A cel painted corner-to-corner takes a sheet that's 10.5 x 9, but one that has a smaller image and is mostly blank will do with one half that size. It does stick to cel paint, but not quickly or tightly.)
I'm finding that the outside cel bags are mostly in perfect condition, though the plastic sheet against the paint has puckered to some degree. So in many cases all I need to do is pull the cel out, flip it over, pull back the corner where the sides are slit, remove the MC paper and inspect the extra sheet. If the puckering is severe, I replace that sheet and maybe renew the MC paper. (Especially if the cel is one that means a lot to me.) It's a relatively quick process and the plus side is that in most cases the cel does not have to be physically handled, just inspected, sniffed, aired out briefly, then returned to storage. I expect that the outside cel bag is probably good to go for another 4 years.
Might be a lot to do for someone with a beginning collection, but I'm finding that the work that I did 4-5 years ago to upgrade my cel books to archival standards is paying off in continued health of the collection and reduced maintenance needs.
That said, I'm doing a complete physical inspection of my collection, some of which has been in my hands for 20 years. The part I'm working on was last rebagged in 2017. I slit my bags down two sides and store them in my Profolios with one slit side facing up toward the opening of the sleeve. And for some time I've put a half or whole sheet of MicroChamber paper in the cel bag, protected from the painted side with an extra plastic sheet (always BPP).
(For newcomers, MicroChamber paper is coated with a chemical surface that adsorbs and neutralizes acidic fumes, increasing the useful age of artwork on plastic, which has the bad habit of chemical instability aka "vinegar syndrome." It's not a cure, as VS arises from inside the plastic sheet, but it does effectively treat the earliest signs of it and so keeps it under control. It's readily available from several sources online; I buy mine in big sheets from Bags Unlimited and cut them to the needed sizes. A cel painted corner-to-corner takes a sheet that's 10.5 x 9, but one that has a smaller image and is mostly blank will do with one half that size. It does stick to cel paint, but not quickly or tightly.)
I'm finding that the outside cel bags are mostly in perfect condition, though the plastic sheet against the paint has puckered to some degree. So in many cases all I need to do is pull the cel out, flip it over, pull back the corner where the sides are slit, remove the MC paper and inspect the extra sheet. If the puckering is severe, I replace that sheet and maybe renew the MC paper. (Especially if the cel is one that means a lot to me.) It's a relatively quick process and the plus side is that in most cases the cel does not have to be physically handled, just inspected, sniffed, aired out briefly, then returned to storage. I expect that the outside cel bag is probably good to go for another 4 years.
Might be a lot to do for someone with a beginning collection, but I'm finding that the work that I did 4-5 years ago to upgrade my cel books to archival standards is paying off in continued health of the collection and reduced maintenance needs.