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Bellows card material?


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What's everyone making bellows cards out of these days? I've seen suggestions of cotton rag board or museum board, but everyone seems to agree that 2 ply is too thin/weak and 4 ply is too thick/bulky (although apparently both have been used successfully). I saw Dana Johnson was using a specific type of presentation board, but I haven't been able to track any down.

 

If it makes any difference, my current plan is for a 7-inch octagonal duet.

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After a lot of experiments I settled on laminating my own card stock from:

 

100 gsm "Canon top colour zero" copier paper

300 gsm "Conqueror connoisseur" 100% cotton card

300 gsm "Conqueror connoisseur" 100% cotton card

100 gsm "Canon top colour zero" copier paper

 

Note that the paper is harder and less stretchy than the card. The paper/card/card/paper combination is thinner, lighter, and stiffer than three layers of card.

 

I use EVA-R acid free bookbinder's glue cut with 10% water, and put it on quite thickly with a foam roller so there's no risk of it delaminating. I think the generous quantity of glue also helps to stiffen the composite without increasing its thickness significantly. I now make it in fairly small pieces because when I tried to laminate large sheets of it I had problems with the glue tacking up before I got it all assembled in the press.

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2 hours ago, alex_holden said:

After a lot of experiments I settled on laminating my own card stock from...

 

Thanks, Alex, I appreciate your specificity in sharing your formula. I don't have a nipping press yet, so I guess I'll add this to the list of justifications for eventually buying one.

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36 minutes ago, Steve Schulteis said:

 

Thanks, Alex, I appreciate your specificity in sharing your formula. I don't have a nipping press yet, so I guess I'll add this to the list of justifications for eventually buying one.


I should clarify that my card laminating press consists of two thick pieces of plywood with wax on them (to stop the glue sticking), and a pile of house bricks. 

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There is a cardboard used widely in the printing and electrical industries called "Presspan" ; this  board is pressed to a uniform thickness, it is very hard and stiff, it is used as a make-ready material in printing and for insulation in electric. It comes in 0.5, 0.7, and 1mm thickness; the 0.7 is 875 gsm. usually in 700mm x 1 mt. sheets, can be cut with a Stanley knife.

This was a semi accidental discovery, before retiring I was in the printing industry; recently I was talking to local builder and repairer Richard Evans about a bellows restoration and he mentioned having difficulty in getting suitable cardboard, I had a couple of sheets of 0.7 presspan in my shed so I gave one to him, he commented that it was the best board he had seen for bellows and did I have any more !

A google search will show local distributers, it's available world wide.

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I didn't find a US distributor that sells small quantities of presspahn, but the site I linked to has affordable shipping to my location. I went ahead and ordered some to see what it's like. I've also got a sample of 300 gsm cotton card on the way, so I can try Alex's lamination approach. Since I don't have the building or repair experience to evaluate each material on its own merits, I also ordered some samples of museum card as a sort of baseline. I won't be building a bellows out of each of these materials, but I'll report back here on their relative stiffness, weight, durability, and workability. If anyone has suggestions for how to test them (or other materials to add to the mix), I'm all ears.

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1 hour ago, Steve Schulteis said:

I didn't find a US distributor that sells small quantities of presspahn, but the site I linked to has affordable shipping to my location. I went ahead and ordered some to see what it's like. I've also got a sample of 300 gsm cotton card on the way, so I can try Alex's lamination approach. Since I don't have the building or repair experience to evaluate each material on its own merits, I also ordered some samples of museum card as a sort of baseline. I won't be building a bellows out of each of these materials, but I'll report back here on their relative stiffness, weight, durability, and workability. If anyone has suggestions for how to test them (or other materials to add to the mix), I'm all ears.

 

1. Good ratio of stiffness to thickness and weight.

2. It shouldn't tear or 'snap' too easily.

3. Glue should stick well to it, and ideally after the glue has fully dried you should be able to pull the hinges fairly hard without the surface layer of the card peeling off.

4. It shouldn't delaminate when you cut it, or when it gets slightly damp, or from repeated flexing.

5. Bit hard to judge this one in advance, but it should ideally remain stable for decades. i.e. acid free.

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  • 2 weeks later...
Posted (edited)

And now, the results of my bellows card material evaluation!

 

I obtained five different types of card:

  • 2-ply cotton museum board
  • 4-ply cotton museum board
  • Holdenesque lamination with 111 lb cotton card as core
  • Holdenesque lamination with 110 lb paper card as core
  • 0.8mm Presspahn

I handled samples of each card, flexed them, cut them, bent them, and generally mangled them in order to develop a subjective assessment. I also performed a couple of more quantitative tests.
 

 

Subjective Analysis

 

The 2-ply museum board and paper-core lamination seemed somewhat comparable in dimension and stiffness, as did the 4-ply museum board and paper-core lamination (note that paper card is about half the thickness of cotton card of the same weight). The Presspahn was unusual, in that it seemed similar to the lighter materials in thickness but closer to the heavier materials in stiffness.
 

When cut with a utility knife, all materials showed a tendency to deform slightly on their bottom surface. Using a fresh blade, a solid cutting surface, and multiple light passes helped reduce or eliminate it. The Presspahn was the most prone to this, and showed some deformation even with very light passes.  I'm unsure if this is a problem, but it seems like it could potentially create a starting point for delamination. The Presspahn was also the most difficult material to cut.
 

With enough rough handling (especially folding a corner), all materials eventually delaminated. It was hard to tell whether any material performed especially well or poorly in resisting delamination as a result of flexing.
 

The 4-ply museum board was especially prone to tearing when folded over on itself. The other materials did tear when folded completely over, but to a lesser degree.
 

I placed a drop of water on each type of card. Presspahn was the big loser here - it absorbed the water quickly and swelled up, easily delaminating. 4-ply was less absorbent, but still delaminated easily. The custom laminations absorbed the water but showed much less swelling and were still resistant to delamination.  The 2-ply was the most water resistant but still delaminated like the 4-ply once it got wet.
 

 

Stiffness Test

 

Samples measuring 28 mm by 101 mm were used for this test.

  1. Each card was placed in a fixture that held it securely by one end and suspended it parallel to the floor.
  2. A weight of 45 grams was attached 60 mm from the secured end, and the card was given time to reach a resting position.
  3. The resulting vertical deflection at the tip (71 mm from the secured end) was measured.

Results

2-ply museum board: 16 mm

4-ply museum board: 6 mm

Cotton-core lamination: 6 mm

Paper-core lamination: 16 mm

Presspahn: 3.5 mm

 

I was a little surprised to see that my comparisons of the 2-ply to the paper-core and the 4-ply to the cotton-core were so on the nose. I was also shocked when the Presspahn turned out to be *more* stiff than even the cotton-core, which was my subjective pick for the sturdiest card.
 

 

Delamination Test

 

Samples measuring 28 mm by 28 mm were used for this test.

  1. Strips of cotton cloth were attached to opposing faces of each card using rabbit skin glue. Each cloth strip covered the entire face it was glued to and extended past the edge of the card. Both cloth strips extended past the same edge of the card.
  2. The card-cloth assembly was suspended by one of the cloth strips, while weight was added to the other cloth strip until the card delaminated. The weight supported at the time of failure was recorded.

Results

2-ply museum board: 757 grams

4-ply museum board: 560 grams

Cotton-core lamination: 739 grams**

Paper-core lamination: < 474 grams (failed to support initial weight)

Presspahn: 693 grams

** The cotton-core suffered an extra jolt at the beginning of its test, which may have contributed to an early failure.

 

This is with a sample size of one, so take these numbers with a hefty grain of salt. Early failures could have been caused by any number of factors that have nothing to do with lamination strength, such as differences in the test glue-up or suspending the weight slightly toward one side of the cloth.
 

I don't see any real pattern here. Between the museum board cards, one did well and the other did poorly. Same with the custom laminations. Between the cards in my lightweight category, one did well and the other did poorly. Same with the heavier cards. Presspahn performed respectably, but wasn't a standout this time.  As with the previous test, the top performer (2-ply!) was a surprise to me.
 

Ultimately, I'm not sure how valid these results are (or even if this is a good test), but I'm probably not going to run the test a dozen more times to get better answers.

 

 

Material Details

 

2-ply Museum Board

Sample thickness: 0.031" (0.787 mm)
Sample density: 0.7 grams/cm³
Deflection under 45 grams: 16 mm
Delamination weight: 757 grams
pH: 8.5-9.5
Lignin-free: Yes
Source: https://www.archivalmethods.com/product/bright-white-2ply-100-cotton-museum-board
 

The tested museum board was buffered. Unbuffered museum board will have a pH closer to 7.
 

4-ply Museum Board

Sample thickness: 0.060" (1.52 mm)
Sample density: 0.66 grams/cm³
Deflection under 45 grams: 6 mm
Delamination weight: 560 grams
pH: 8.5-9.5
Lignin-free: Yes
Source: https://www.archivalmethods.com/product/antique-white-4-ply-100-cotton-museum-board
 

The samples received included multiple colors of 4-ply museum board. Each sample had a uniform thickness, but there was variation between them from 0.058" to 0.063". The card that the label separated from most cleanly was selected for testing.

 

The tested museum board was buffered. Unbuffered museum board will have a pH closer to 7.
 

Cotton-Core Holdenesque Lamination

Sample thickness: 0.055" (1.40 mm)
Sample density: 0.69 grams/cm³
Deflection under 45 grams: 6 mm
Delamination weight: 739 grams
pH: "acid-free" for paper, "acid-free" for card stock, 7.1-7.3 for adhesive
Lignin-free: Unspecified for paper, yes for card stock
Sources:

This card consisted of four layers laminated with Jade R adhesive plus 10% water by mass:

  1. 28 lb printer paper
  2. 111 lb 100% cotton card stock
  3. 111 lb 100% cotton card stock
  4. 28 lb printer paper

This was my attempt to stick as close to Alex Holden's original formula as I could.

 

Paper-Core Holdenesque Lamination

Sample thickness: 0.037" (0.940 mm)
Sample density: 0.87 grams/cm³
Deflection under 45 grams: 16 mm
Delamination weight: < 474 grams
pH: "acid-free" for paper, "acid-free" for card stock, 7.1-7.3 for adhesive
Lignin-free: Unspecified
Sources:

This card consisted of four layers laminated with Jade R adhesive plus 10% water by mass:

  1. 28 lb printer paper
  2. 110 lb card stock
  3. 110 lb card stock
  4. 28 lb printer paper

0.8 mm Presspahn

Sample thickness: 0.037" (0.940 mm)
Sample density: 0.92 grams/cm³
Deflection under 45 grams: 3.5 mm
Delamination weight: 693 grams
pH: 7.0 - 8.5
Lignin-free: Unspecified, but likely yes
Source: https://secure.presspahn.com/Cart/index.php?main_page=product_info&cPath=1_11&products_id=34
 

A specific type (Grade K) of "Elephantide", which is a brand of electrical pressboard. While pressboard can be made from a variety of materials, Presspahn is made from kraft wood pulp.  More details are available at https://secure.presspahn.com/Products/Whiteley/GradeK.htm or https://www.presspahn.com/product-solutions/material-solutions/100-presspahn/
 

 

Conclusion

 

My pick for the best all-around material is Alex Holden's original lamination formula. I'm sure he's done a lot of his own experimentation to arrive at it, so that isn't any great surprise.

 

Even thought it's not my top pick, I think I'm still going to make a full bellows with the Presspahn - I've got enough of it on hand already, and it lets me skip the extra lamination step. It will be interesting to see how it holds up over time.

Edited by Steve Schulteis
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Thanks for taking the time to do such a detailed analysis, Steve! The Presspahn certainly sounds like it has some advantages. Its poor water resistance would be my main concern as I make a lot of use of a hot damp sponge to smooth the leather down and remove excess glue.

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6 hours ago, alex_holden said:

Its poor water resistance would be my main concern as I make a lot of use of a hot damp sponge to smooth the leather down and remove excess glue.

 

Yeah, that would be an issue. Any place the sponge makes direct contact with the card would be at serious risk.

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I've just made a set using very thin plywood, I think I used 0.8mm. Worked very well, and for the strength didn't bulk up the folds as much as card does. Any reason why this isn't used more often, other than tradition and increased difficulty in shaping? I use the "Tedrow" method, as they are cut together as a strip on the bandsaw it really made no odds, actually was cleaner to cut than card.

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16 hours ago, Pistachio Dreamer said:

I've just made a set using very thin plywood, I think I used 0.8mm. Worked very well, and for the strength didn't bulk up the folds as much as card does. Any reason why this isn't used more often, other than tradition and increased difficulty in shaping? I use the "Tedrow" method, as they are cut together as a strip on the bandsaw it really made no odds, actually was cleaner to cut than card.

 

I've wondered this very thing, although for some reason it hadn't occurred to me that you could get ready-made plywood this thin until your post (I had been thinking about laminating veneers and controlling thickness with a drum sander).

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8 hours ago, Steve Schulteis said:

 

I've wondered this very thing, although for some reason it hadn't occurred to me that you could get ready-made plywood this thin until your post (I had been thinking about laminating veneers and controlling thickness with a drum sander).

Yes, it's very easy to find in model making shops

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