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Old 01-17-2020, 05:55 PM
steve B steve B is offline
Steve Birmingham
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Join Date: Sep 2009
Location: eastern Mass.
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Quote:
Originally Posted by Goudey77 View Post
Steve B, Glad that my sarcasm resulted in some real world information. Thanks for the knowledge drop.

Not so kidding aside does extreme fluctuations in humidity/drying in the air potentially cause warping and or shrinkage in typical card stock?

Let's say even a good old soak job?
Warping - Sort of. The non- coated side would expand more because it isn't sealed. Measuring a pretty serious warp and doing a bit of math, if the center is warped up by .61 (measuring a warp similar to my worst by bending a junk common and measuring how high the center is. )
Then the difference in length between the front and back is only about .005 Inches. Or about 1.6% And that's equivalent to the most warped cards I've seen.

Soaking should do that, but what usually happens if you soak and just leave it out is that the fibers expand in a somewhat random way, leaving a wrinkly surface that we'd all recognize as water damage.
Pressing flat to dry usually fixes that, but by forcing the fibers into sort of their original locations - Unless the soak removed too much seizing, or glue from between layers.

Excess humidity would expand a card slightly. I'd have to see about borrowing the moisture content meter from the makerspace woodshop, or buy my own to get some reliable numbers.
The Stamp sheets that they tried different spacing on were about 2 ft across, and they expanded the spacing by 1mm on four rows. (It didn't actually work, probably because the drying was dependent on the ambient temperature and humidity so the sheets shrunk sort of randomly. )
so you can see there wasn't much shrinkage expected in a paper that had a decent rag content.

The card in question is visibly short both ways, even going on a conservative 1/64th of an inch that's roughly 3x what I'd expect from humidity.

I've never tried shrinking a card. If it's very humid and I bake it, maybe. But I'd expect about as much as the warped cards.
Sounds like an experiment that should be done.
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