here's hoping for a consistently dense thread

December 12, 2018 1:49 PM

Got some fabric, want to check it for thread count or imperfections, and you can only use the power of moire? Looks like you need a Lunometer! The device was invented, patented in 1929, and eponymously branded by one Hans Peter Luhn, who also invented the goddam hashing algorithm among other things.
posted by cortex (13 comments total)

as someone tangentially involved in textiles who mainly works in IT, seeing these weird overlaps always makes me excited and happy.
posted by jrishel at 2:03 PM on December 12, 2018 [1 favorite]

*drool*
posted by Melismata at 2:07 PM on December 12, 2018

I have a 2 similar sheets of plastic that I use to check the line screen ruling on halftone films & the thread count of silkscreen frames.

I got pretty good at halftone printing a while ago, but one of the biggest bugbears was finding 3 different screen angles I could use for CMYK film seps without any of them moire-ing (spelling? is that a word?) against the screen mesh. It's funny -- 55 line was easy, but pretty coarse, 65 took a bit of work, 75 was RIGHT OUT but at 85 line, things smoothed out again. I determined the best angles for the film by printing a test film at 0º them placing it on an uncoated screen on a light table, & turning the film until the moire disappeared, then measuring the angle with a T-square & a protractor. Finding three that were 30º apart, but that all worked on the same screen mesh took an afternoon, but once I got it, there it was, & it's been trouble-free ever since. It blows some customers minds that I can print on a T-shirt at 85 line screen, but really, it just took an idea and an few day's worth of research (98º, 128º, 158º on 355/31 micron mesh, in case you were wondering) & I had me a niche.

Staring at all those moire patterns getting bigger & smaller as I turned the film made me kinda dizzy, though.
posted by Devils Rancher at 2:56 PM on December 12, 2018 [4 favorites]

I used to have something similar in my draw for years and used it every day. I used it to measure halftone screen angles. It was made of transparent plastic and had Xx heights for point sizes as well as line thickness examples on it. Thanks for the memories, I haven't thought about it in a long time.
posted by unliteral at 3:04 PM on December 12, 2018

He had quite a range of interests and accomplishments! From the last link, "During the 1930s, his numerous patents included a foldable raincoat, a device for shaping women’s stockings, a game table, and the “Cocktail Oracle”—a guide that told the user what drinks could be made from the ingredients on hand."

Also, cortex, I much admire your phase, goddam hashing algorithm.
posted by a humble nudibranch at 3:58 PM on December 12, 2018

I found this strangely compelling (to me) wordless video showing how to use one.
posted by doift at 9:30 PM on December 12, 2018 [1 favorite]

I want to buy something like this in the US, but I'm not sure how to search for it online, other then lunometer, which returns no results on amazon. Is there a generic term?
posted by gryftir at 10:01 PM on December 12, 2018

I've always loved hash tables, they're my favorite data structure, but I need a cocktail oracle!
posted by monotreme at 11:41 PM on December 12, 2018 [1 favorite]

gryftir: I want to buy something like this in the US, but I'm not sure how to search for it online, other then lunometer, which returns no results on amazon.

Through some googling I found this place, which sells them. There are a few other places, but that was the only only which gave a price.
posted by Kattullus at 3:07 AM on December 13, 2018

J.A. King is the official reseller of lunometers in the US, according to the Lunometer website.
posted by ardgedee at 4:29 AM on December 13, 2018

I need a cocktail oracle!

Fittingly, this Luhn's information processing tool is available online.
posted by hat_eater at 6:08 AM on December 13, 2018 [1 favorite]

I'm really disappointed by the lack of puns in this thread. I thought there'd be moire.
posted by phooky at 6:28 AM on December 13, 2018 [1 favorite]

The thread count of puns was lame, if not the absolute worsted. Usually you can count on this homespun, motley bunch of cretonnes to have a warped sense of humor. So of course you felt fleeced.
posted by mubba at 7:52 AM on December 13, 2018 [4 favorites]