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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
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
I have sent this to our framing housing expert.
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.
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.
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.
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
Hugh Phibbs, Preservation Specialist
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