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MITRA Forum Question Details

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  • Coroplast acid free versus regularApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2019-08-23 12:33:46 ... Most recent comment 2019-08-26 16:34:52
    Matting, Framing, and Glazing Industrial and Non-Traditional Products Other Rigid Supports

    I am considering using Coroplast as a support for large (48 x 48) drawings  on archival Tyvek. My main question is whether I need to use acid free or if standard white coroplast is neutral an inert. See more details below.

    I have an exhibition coming up very soon that I need to prepare for. My original solution was to use acid free foamcore but its arriving with dented edges so I am exploring alternative more durable materials.

    I will use acid free tape to adhere the drawings​ to what ever support I will use. There will not be a frame, but the work will be protected by a sheet of plexiglass that will be spaced away from the work. L screws will mount the work to the wall with custom spacers to separate glazing from the drawings.

    In some research online I came across a discussion stating that there is no difference in acidity between the acid free coroplast and colored coroplast that is not acid free (white or clear is what I would prefer). It may be easier to find the regular coroplast locally in the large sheets that I need which is why I am asking if there is a significant difference. I may be able to line the support with an extra sheet of Tyvek as a barrier if that would be necessary.

    thanks very much!

Answers and Comments

  • EditDeleteModerator Answer

    ​I have sent this to our framing housing expert.

    Brian Baade
    2019-08-23 13:09:23
  • EditDeleteModerator Answer

    “Archival” Coroplast is actually free of additives, while Coroplast is free of acid. They leave out UV inhibitors and anti-oxidants and colorants. There may still be slip or release agents, left on the surface, which means that it is not a material intended for contact with art. If you are drawing on plastic, keeping the acrylic away is likely to be a waste of effort, since static will draw the support sheet forward, in all likelihood. Using anything pressure-sensitive is going to cause problems. The drawings laid on a same size sheet of paper and sandwiched between the Coroplast and the glazing sheet, both of which should be slightly larger than the drawing. The edges of this sandwich can be taped with a good quality tape like 3M 850, or 450, after a strip of mylar has been placed between the edge of the package and the tape’s adhesive layer. to keep the sticky stuff at bay. Thought should be given as to how these packages will hang. One possibility is to make the Coroplast panels larger than the art, by a few inches and then score it to get the size that is just larger than the drawing. The board is bent open along the scores, after the corners have been cut, on the diagonal, so that they will not overlap at the corners. The outer portion can be folded in and taped flat and slits can be made, through the fold, where the hangers will be. Mylar strips can be threaded through those slits and taped into loops, where they are closest to the canter of the art, so that a hanging wire/twine can be secured to them. 

    Hugh Phibbs.

    2019-08-23 14:12:20
  • EditDeleteModerator Answer

    ​To echo part of Hugh's recommendation, I would steer clear of using any kind of tape directly on your art - even if it says "acid free" or "archival."  Those tend to be just as problematic as "regular" tape as they age.

    I've used regular coroplast covered with Tyvek as a rigid transport surface for art and it worked well.

    Gillian Marcus
    2019-08-23 18:45:09
  • ApproveRejectUn-ApproveUser Comment

    Thanks very much Hugh and Gillian for reviewing and answering my questions.  I have a couple of follow up questions after giving your suggestions much thought over the weekend.

    First question:

    Brian, are you are suggesting that the drawing be placed in direct contact with the Plexi? I thought it was never advisable for art to be in direct contact with the glazing material?

    I am working with Caran D' Ache Neocolor I (wax, not water soluble) drawn over Golden acrylic glazes built up in several layers (paint 50/50 with Fluid Matte Medium) which were applied by rubbing onto archival Tyvek (10G).  They will be finished with a Lascaux Protective UV Finish.

    I did a test a few months ago with a small sample that I laid flat and placed directly on top of the art with a 2 pound weight on top for a week. Nothing adhered to the plexi, but I was still leery of placing the art directly into contact with the drawing.

    Second question - need clarification before ordering the  Coroplast today  (I am running out of time to mount the drawings for an exhibition.):

     Is it worth the extra cost and difficulty of obtaining  the Archival Coroplast?  Or, is the regular Coroplast ok, since its also acid free – do the other additives pose much of a danger to the Tyvek?  I also would prefer to have a white sheet, available in the regular coroplast, rather than the translucent color of the archival if it is not too risky.

    Thanks again for your expertise!

    2019-08-25 16:28:10
  • ApproveRejectUn-ApproveUser Comment

    ​I forgot to add that the acid free tape I would use is this one by Gudy which says it is removal with glass cleaner or ethanol:

    I think I need to use some sort of double stick tape to be sure the drawing remains taut. I only need to apply the tape to the corners and maybe one or two positions along the edge.

    excerpts from the technical manual for the tape

    Gudy dot is in an easy to use double sided tape in a convenient ergonomic dispenser roll. The "dot-shaped" adhesive coating makes the material easier to handle and allows bubble free positioning. The tape is a waterbased adhesive and environmentally friendly. 

    Processing & Handling - to avoid problems in processing/lamination ensure adequate drying before lamination- drying time of min. 24 hours is recommended. - for self-adhesive finishing of photos, inkjet- or digital prints in a lamination machine, we recommend to use a smaller width of the mounting film gudy dot than the laminated material - surfaces must be properly prepared and free of contamination - the removability depends on the media-combination and the surface and cannot be guaranteed. We recommend customers conduct their own tests to see if the material is qualified for the actual end-use.

    - possibly arising adhesive residues can be removed from smooth, non absorbant substrates with a cloth soaked in glass-cleaner or ethanol - gudy dot is not recommended for mounting on or behind acrylic glass. For these of applications we recommend “gudy window”. You can find all available product information on our homepage: storage is best to be done in upright position in the original case  

    2019-08-25 16:34:08
  • ApproveRejectUn-ApproveUser Comment

    ​Hugh, my appologies (and to Brian) I meant to address the question about plexi in contact with the artwork to you. 

    2019-08-25 22:54:22
  • EditDeleteModerator Answer

    ​I would still hesitate to use the Gudy adhesive, even if their website says it can be removed with glass cleaner or ethanol.  As tape ages, the adhesive becomes resistant to solvents and techniques that work when it is freshly applied.  I also would avoid applying glass cleaner anywehere near your art!  

    I would also err towards using the archival Coroplast if possible; however, if you are pressed for time and the "regular" Coroplast is all that is available, I would simply use it only for display and store the Tyvek piece separate from the Coroplast (or with a buffering material in between) afterward.   

    Gillian Marcus
    2019-08-26 13:18:23
  • EditDeleteModerator Answer

    ​Contact between acrylic sheet and art may be less consequential than contact between glass and art work. Glass is much harder than acrylic and glass is thermal reservoir, while acrylic is a thermal insulator, which means that when morning sun goes through glass, the glass stays cold, while the infra red in the sunlight warms the art and drives out moisture, which can condense on the cool glass. This is much less likely with acrylic, but acrylic can sustain a static charge more than glass can. Some media can be flattened by contact with either glazing sheet and if acrylic media sticks to acrylic sheet, it can pose a problem, since they will be chemically similar and must be parted physically. For that reason, spacing the acrylic sheet away from the art work described, here, is wise, but ensuring a complete absence of contact will be difficult to ensure. A spacer of Volara can be secured to the acrylic sheet with pressure sensitive adhesive, but static may pull the Tyvek forward and if 4 mil Coroplast is used, it will be flexible enough that it and the acrylic sheet may bend together near the center. The added expense of additive free, “archival” Coroplast is not needed and using a thicker version, 6, 8, 10 mil can make successful spacing easier to achieve.  If the art is to be held back, it will need adhesion to the support and while many water based adhesives can bond to flash spun polyethylene, Tyvek, they will not stick to the polypropylene of the Coroplast. The only safe adhesive that can be used for such hinging is Klucel G, hydroxy propyl cellulose, in a viscous form, (one part powder/one part solvent) since it has surfactant properties. It can be mixed with water or isopropyl alcohol, since all the bonding will be with plastic materials and it must be tested carefully, before being employed.

    Hugh Phibbs, Preservation Specialist

    2019-08-26 16:34:52

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