PVC NOT REALLY A BAD GUY!
Moderators: Daniel Jackson, greg
PVC NOT REALLY A BAD GUY!
Here is a post(on CGC boards) from a guy with a LOT more time on his hands than me!
Quote"The use of PVC's was once very common in plastic storage sheets for baseball cards -- everything from storage pages produced by ENOR corporation to Rotman PS 1000 TLs to Safe-T-Durapages produced by U.S. Gerslyn, Ltd. to Protecto CC-8s made by Cal-Cards Ltd. Many of these sheets are over 20 years old and some may even be closer to 30. To this day, I still keep many vintage baseball cards stored in these sheets and I have yet to observe any damage. Some of the sheets have even turned yellow but the baseball cards remain totally unscathed.
How can this be? According to some informal reports on the Internet, Polyvinyl Chlorides (PVC's) can cause "paper products [to] dry out completely making them brittle to the touch" or "can also cause a brown discoloration after a number of years...." (Source citation).
The problem with this analysis is that no scientific testing is offered as support -- i.e., it is presented in editorialized, pseudo-scientific form (much like an infomercial for oxyclean or a special wax that removes scratches from cars).
PVC is actually a common thermoplastic resin used in a wide variety of manufactured products. It is also used in the packaging of processed meats, pasta and in some industrial applications (Source). Because the molecules in linear polymers such as PVC are long chains of monomers joined by rigid bonds that prevent monomers from rotating, properties include being a good oxygen barrier and having good chemical resistance.
It is important to note that there are many different types of PVC inclusions. There is lightly plasticized PVC, orientated PVC, normal plasticized PVC and heavily plasticized PVC. The type of PVC inclusion will undoubtedly affect a substance's archival properties. Low amounts of PVC's can remain relatively inert for extended periods of time. I know. I've used plastic sheets containing PVC's to store baseball cards for over two decades with no adverse effects. Also, some Polyvinyl Chloride extractions are combined with other agents such as tri-creylphosphate to produce odorless and acid-resistant synthetics, so the term "PVC" should not always be associated with collectibles in a negative light.
I think one of the misperceptions that has developed in this thread is that non-PVC plastics are archivally safe. This is not necessarily the case. The inclusion of plasticizers or certain solvents can render even the most inert polymers chemically reactive. As a result, some compounds may eventually leech from the plastic film and come into contact with the item being protected. A good example of this phenomenon was produced in a FTIR spectroscopy test conducted by J. Mason Associates in January 2001 (hosted by the American Association of Comicbook Collectors) -- previous link.
This investigation determined that "Every plastic film has its strengths and it’s [sic] weaknesses in each of these areas and no two are alike. Some are excellent moisture barriers but poor gas barriers. Others are excellent gas barriers but poor moisture barriers. Generally, the better the gas barrier, the poorer the moisture barrier." Applying this information to both PVC and Barex we find that PVC does a better job of blocking moisture but Barex has a lower gas transmission rate (Source).
[Note: Barex is a high nitrite polymer suitable for all types of packaging. It offers high gas barrier and excellent chemical resistance. Barex is also referred to as a rubber-modified copolymer of acrylonitrile and methylacrylate -- a type of polyester. Comparatively speaking, Barex has a much higher cost than PVC.]
Interestingly, the FTIR tests also revealed that "in the samples that were submitted for testing, every sample seems to contain an ultraviolet inhibitor which would render each and every sample unsuitable for use by the Library of Congress." And yes, that includes both Barex that is used in the CGC interior holder and Styrene Acrylonitrile Copolymer (SAN) which is used in the CGC exterior holder.
So just what SHOULD be used for complete archival protection? Well, according to the US Library of Congress, the preferred material for preserving valuable documents is uncoated archival quality polyester film, such as Mylar® type D or equivalent material such as Melinex® 516 (Source).
I think that one problem with the ARDL test (see first post in thread) is that it never specified the type of PVC nor the percent inclusion of PVC in the CGG holder. To that extent, any judgments made about the archival properties of the CGG holder are without any substantial scientific support. It may very well be that CGG holders contain Barex just like CGC holders or that the CGC holders contain PVCs in addition to Barex. All that the ARDL test proved (allegedly) is that PVC was a detected polymer.
A good resource for more information on this subject and conservation would be the AIC:
The American Institute for Conservation of Historic and Artistic Works (AIC) and FAIC Conservation Services Referral System, 1717 K Street N.W. Suite 301, Washington, D.C. 20006; Telephone: (202) 452-9545; Fax: (202) 452-9328. "
Quote"The use of PVC's was once very common in plastic storage sheets for baseball cards -- everything from storage pages produced by ENOR corporation to Rotman PS 1000 TLs to Safe-T-Durapages produced by U.S. Gerslyn, Ltd. to Protecto CC-8s made by Cal-Cards Ltd. Many of these sheets are over 20 years old and some may even be closer to 30. To this day, I still keep many vintage baseball cards stored in these sheets and I have yet to observe any damage. Some of the sheets have even turned yellow but the baseball cards remain totally unscathed.
How can this be? According to some informal reports on the Internet, Polyvinyl Chlorides (PVC's) can cause "paper products [to] dry out completely making them brittle to the touch" or "can also cause a brown discoloration after a number of years...." (Source citation).
The problem with this analysis is that no scientific testing is offered as support -- i.e., it is presented in editorialized, pseudo-scientific form (much like an infomercial for oxyclean or a special wax that removes scratches from cars).
PVC is actually a common thermoplastic resin used in a wide variety of manufactured products. It is also used in the packaging of processed meats, pasta and in some industrial applications (Source). Because the molecules in linear polymers such as PVC are long chains of monomers joined by rigid bonds that prevent monomers from rotating, properties include being a good oxygen barrier and having good chemical resistance.
It is important to note that there are many different types of PVC inclusions. There is lightly plasticized PVC, orientated PVC, normal plasticized PVC and heavily plasticized PVC. The type of PVC inclusion will undoubtedly affect a substance's archival properties. Low amounts of PVC's can remain relatively inert for extended periods of time. I know. I've used plastic sheets containing PVC's to store baseball cards for over two decades with no adverse effects. Also, some Polyvinyl Chloride extractions are combined with other agents such as tri-creylphosphate to produce odorless and acid-resistant synthetics, so the term "PVC" should not always be associated with collectibles in a negative light.
I think one of the misperceptions that has developed in this thread is that non-PVC plastics are archivally safe. This is not necessarily the case. The inclusion of plasticizers or certain solvents can render even the most inert polymers chemically reactive. As a result, some compounds may eventually leech from the plastic film and come into contact with the item being protected. A good example of this phenomenon was produced in a FTIR spectroscopy test conducted by J. Mason Associates in January 2001 (hosted by the American Association of Comicbook Collectors) -- previous link.
This investigation determined that "Every plastic film has its strengths and it’s [sic] weaknesses in each of these areas and no two are alike. Some are excellent moisture barriers but poor gas barriers. Others are excellent gas barriers but poor moisture barriers. Generally, the better the gas barrier, the poorer the moisture barrier." Applying this information to both PVC and Barex we find that PVC does a better job of blocking moisture but Barex has a lower gas transmission rate (Source).
[Note: Barex is a high nitrite polymer suitable for all types of packaging. It offers high gas barrier and excellent chemical resistance. Barex is also referred to as a rubber-modified copolymer of acrylonitrile and methylacrylate -- a type of polyester. Comparatively speaking, Barex has a much higher cost than PVC.]
Interestingly, the FTIR tests also revealed that "in the samples that were submitted for testing, every sample seems to contain an ultraviolet inhibitor which would render each and every sample unsuitable for use by the Library of Congress." And yes, that includes both Barex that is used in the CGC interior holder and Styrene Acrylonitrile Copolymer (SAN) which is used in the CGC exterior holder.
So just what SHOULD be used for complete archival protection? Well, according to the US Library of Congress, the preferred material for preserving valuable documents is uncoated archival quality polyester film, such as Mylar® type D or equivalent material such as Melinex® 516 (Source).
I think that one problem with the ARDL test (see first post in thread) is that it never specified the type of PVC nor the percent inclusion of PVC in the CGG holder. To that extent, any judgments made about the archival properties of the CGG holder are without any substantial scientific support. It may very well be that CGG holders contain Barex just like CGC holders or that the CGC holders contain PVCs in addition to Barex. All that the ARDL test proved (allegedly) is that PVC was a detected polymer.
A good resource for more information on this subject and conservation would be the AIC:
The American Institute for Conservation of Historic and Artistic Works (AIC) and FAIC Conservation Services Referral System, 1717 K Street N.W. Suite 301, Washington, D.C. 20006; Telephone: (202) 452-9545; Fax: (202) 452-9328. "