Shadowbox backing dilemma

[Carol Neff]

I had a customer bring in an old Red Sox jacket (which is a heavier jacket), cap and ball. I know how I would like to put this all together and pretty much know how, but I'm wondering if foamcore is going to be enough for a backing for this project? I've looked in the forum archives and didn't really find anything similar. Any help would be greatly appreciated!

 

[Walt C]

Coroplast is my choice for heavy items like this.

 

[Cliff Wilson]

I might suggest two sheets of coroplast and run the ribs in opposing directions.

 

[Carol Neff]

I've never used coroplast. What is it and where do you get it?

 

[Jim Miller]

The generic term is "fluted polypropylene". Coroplast and Matraplast are popular brand names. This is a sheet plastic product commonly used for signs with stick-on vinyl letters.

It is normally sold through distributors to the sign-making industry, available in 48"x96" sheets; expect to pay $6.00 to $9.00 per sheet. If you can't find one of those in your area, you could probably buy it cut-to-size from a sign maker, but you'll pay more for it that way.

For your application I suggest using two layers of 4 mm or 6 mm thickness with the flutes crossed, as Cliff said. You can stick them together with strips of 3M #8898 double-sided tape.

White and black are good color choices -- we stock both in our shop & use this product regularly.

 

[FramingFool]

Short of the coroplast (which is great ...), you might consider using Gatorfoam ... stout stuff.

 

[Jay H]

I use 2 things typically. Foamcore or plywood.

 

[Cliff Wilson]

Jay, Jay, Jay, get some "fluted polypropylene." It will probably save you some money, be lighter, and it's inert.

I found a distributor here in MA that sells non-colored in 32 x 40 sheets 25 to a box for 79.50 plus shipping. (Smallcorp, Inc)

A little more than your cost Jim, but it "fits" better in my storage, workflow, etc.

I have been trying to get one of the local distributors, or LJ to carry it. Would make things a lot easier and save on shipping.

 

[Ron Eggers]

I wonder how widely used Coroplast is outside of the Grumble framing community? I never heard of it until Jim Miller started raving about it. I discovered then that Vicki Schober was stocking it and delivering it with matboard orders to our area.

Alas, it appears that John Ranes and I were the only ones interested and Vicki dropped it. Between the two of us, we bought up most of the remaining stock.

 

[Dave]

Are their any issues with outgasing or other migratory problems with Coroplast?

I have several hundred sheets which I could use as backing or filler board. I sporadically sell 50-200 cut sheets to a manufacturer for signage and am left with the cut-offs which usually are around 24X36 or larger. I have been using the scrap for shipping, as a waterproof surface when I fabric wrap mats, as a fit-up table protector when I work on old nasty frames and a multitude of other uses. I usually end up giving a few hundred sheets away to schools or churches for temporary outdoor signage each year.

I'd love to use it more in a frame package if you know there to be no problems.

Your suggestion of cross directional corrugation is excellent. It really makes the board quite rigid. When I use it for shipping I cross direction each side of the package and it wouldn't bend if you tried your darndest.

I buy it from a distributor in 4X8 4mm sheets and pay $ 6.50 a sheet for white 10+ sheets plus a $ 20.00 delivery fee on their truck. Price drops slightly on 50 sheets. I'm somewhat ashamed to tell you the profit margin you can make selling commercially depending on your market. Hey, we gotta make it somewhere!

The stuff cuts like butter on a mat cutter or with a razor blade. Cleans up beautifully with glass cleaner. It's waterproof and excellent for temporary outdoor signage. You can also buy metal stands which stick into the flutes for yard signs, etc. I had my distributor cut it only once and never again...they used a saw and the edges were melted together and rough. I had to sliver each side of the board before delivery to my customer.

Thanks for any help with the conservation issues. I'm hopeful that I can safely use it for other applications.

Dave Makielski

 

[Ron Eggers]

Someone can elaborate, but . . .

Coroplast used by sign makers will have UV inhibitors and anti-oxidants that enhance the outdoor performance but add chemicals un-needed and possibly detrimental to some framing applications.

Clear is more inert than colored.

Smallcorp and a few others supply archival Polyflute but for most framing applications, the regular is wonderful stuff.

I have some technical notes in an email somewhere and I'll see if I can excavate them.

 

[Jim Miller]

Originally posted by Cliff Wilson:
...I found a distributor here in MA that sells non-colored in 32 x 40 sheets 25 to a box for 79.50 plus shipping. (Smallcorp, Inc)

Cliff:

If you are referring to the translucent "archival" Coroplast, I buy that same product from Small Corp.

Coroplast claims that it is the best product for preservation framing, because it is made without additives, such as colorants or UV inhibitors, which could chemically react in certain situations (for example, high heat).

However, I've talked with a few museum people who use the common, colored Coroplast to make storage boxes for museum artifacts. They're not concerned about its chemical content & say it is equally preservation-worthy.

 

[Dave]

As always, you folks are a wealth of information. Thanks.

Dave Makielski

 

[Cliff Wilson]

Jim, yes, that is the product I am refering to and I heard the same thing about the colored. I buy the "archival" because it's the only thing they sell in the 32 x 40 boxed format.

Dave, from what I understand from the chemist I've talked to, (and others like Jim) you can't use anything more inert. I usually like to use it in back of Artcare (in case that stuff really does obsorb bad things. )

 

[Carol Neff]

Thank you everyone for your input. I learn so much out here on The Grumble!!!

I've contacted Small Corp and they are sending me a catalog.

 

[preservator]

Great thread, all.

Hugh

 

[wpfay]

I've been experimenting with welding the polyflute panels together using hot melt glue. I first cut and position the panels with the flutes perpendicular to one another and make an opening through the top 3 layers (I initially used a drill bit with tape on it to limit depth of the hole, but quickly found out that the tip of the glue gun works kwite nicely). I inject the glue as I withdraw the gun making an "X" shaped tack weld. I use the GE non-corrosive hot melt glue from SmallCorp and the big orange gun I got from UMS. A pattern of every 6-8" seems to hold the panels together very well. Any weld "buttons" can be quickly spread out (I use a piece of mat board) while the glue is still molten, or trimmed off with a razor blade after cooling.
I have also used a similar method when splicing polyflute for oversize application.