Identifying plate manufacturer

Is there a way to identify the polymer plate manufacturer and the type of the plate?

I suspect substitution. Or even worst: I am getting the “new and improved” version of the same plate!

The new plates I am receiving feel flimsier, softer in my hands. When I am cutting them they develop more bow, distortion and the polymer material produces more swarf along the cut edge. Otherwise they look identical to the old ones, even dimensionally.

I purchased a Shore-D hardness tester and tested some leftover material from the old stock and the new stock to compare. I made small squares and processed them as regular plates, except the film and wash-out.
Could not find any published standard for testing steel backed printing plates, so I experimented. I do not know how to eliminate the anvil effect on the hardness value and how long to test. I think that the nominal hardness is the initial hardness including the anvil effect for the given thickness. I tested other plate material too, and the results point in this direction.

Well, the initial hardness of my new plates are not as high as advertised, but to my bigger surprise, the hardness creep is enormous over time. The test needle keeps on sinking in to the material, approximately 1deg. per second.
On the contrary, the old materials’ initial hardness is as advertised and the hardness creep is only 2deg. per 15 seconds!
The old plates were more resilient and able to keep the fine lines when washed-out. On the new ones I noticed plate erosion too after ~250 heavy impressions.

Both the old and the new plates come from my long time and reputable supplier with the same product code. I sourced the same plates from an alternate source, and the test results were the same as on my old plates.

I really can’t identify the plates just by looking at them, but I feel that something is wrong here.


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My first question would be: did you speak to your supplier about this? They may be able to shed some light on the situation.

Regarding durometer, durometer measurements are supposed to be taken on material with a minimum of 6.4 mm (1/4”) thickness, to avoid having the hardness of the plate backing (or whatever hard surface the plate is resting on), affect the readings. Also, if you Google how to take durometer readings, they say the readings should be taken after 15 seconds. However, we never did this when taking Shore A durometer readings of rubber rollers….we always were taught to take them immediately….so I don’t know if the photopolymer people take them immediately or not.

Regardless of the procedure, you have used your Shore D durometer to identify differences in the plates and I commend you for doing that. It goes along with the old industrial adage, “If you can’t measure it, you can’t control it.”

Regarding whether you might have a “new improved version,” that could be possible. I notice on Toyobo’s website they do list a couple of “new” plates:

I wonder if you could make the “new” plates perform better if you changed the exposure and washout parameters. (For example, with soft photopolymer flexo plates, we were supposed to make a new exposure test for every new batch of raw plate material we got from our supplier). Maybe if you increased the exposure time or made other changes, the new material might perform OK.

Just a few thoughts……please keep us posted on your progress.

hello Geoffrey,
thank you for your input.

Yes, I did ask them. First I was puzzled by the description field, so I wanted some clarification on that. The description is:

and they sent along a MIRACLON MSD sheet.

It looks to me that their product code can include any of the three different plates. Even the manufacturers are different.

After a while, they came back with the answer that they don’t understand my question. So, second time around I was more direct: who is the manufacturer and the original product code of the last batch of plates you have sent me?

The answer was: JetUSA LSL-145 HSB

That is when I sourced the above plates from a different supplier and did the tests. The findings are in my original post. They don’t feel the same. But what do I know, I am not an expert, I am just a printer!

Surprisingly none of the plates have markings on them, like; manufacturer, type of plate, lot/batch number and date of manufacture … et cetera.

I find it odd, that the common construction grade sheet of plywood has all that information stamped all over it, and that the expensive sheet of photo-polymer does not!

It looks like that not just our photo-polymer plates but WE could be “exposed” to the whim of our suppliers!


regarding your thoughts about lengthening the exposure, I read somewhere that prolonged exposure might actually weaken the polymer. Probably heat hardening the plates would give better results. Someone actually went as far as to patent the process. Blowing hot air is now patented !

Check it out: US Patent 4,264,712


Hello Louie,

If you look at the second chart down on the page in the link, under LSL-145-SB, you will see that the polymer used for the plate is P.V.A. (polyvinyl acetate or polyvinyl alcohol, I can’t remember which):

However, for some other plates in the chart, Nylon (DuPont trademark) is used for the polymer. It would be my guess (and it is just a guess), that the plates you like are Nylon and the ones you don’t like are P.V.A.

Regarding hardening of plates, the way I understand it, unexposed plate material is composed of relatively small molecules. When you subject plate material to UV light during exposure, you cause the molecules in the polymer to link together to form larger molecules which are more rigid. The longer you expose the material to UV, the more the molecules link together. Eventually the polymer gets so rigid that it gets brittle and can crack. (The cracks may not appear right away). I don’t think that increasing exposure time a moderate amount is likely to damage the plate but only experimentation will tell.

Regarding heat hardening of plates, it might work if you use metal backed plates, but not for polyester backed plates. The polyester can’t take too much heat or you lose the dimensional stability of the backing. We were taught not to exceed 140 degrees F.

hello Geoffrey,

I am talking LSL 154 HSB ( there is a H before the SB )

I have a SAMPLE of this plate. It is a solid performer, and I like it, with 90 deg.Shore D. For some reason it did not made it to the JetUSA web page but it is available:

Interestingly, Boxcar Press quotes its hardness as 85 deg. Shore D. My tests indicate the 90 as it is claimed by JetUSA.

According to JetUSA their product nomenclature is:

LSL-###-SSSB = 25° D Super Soft Steel Back
LSL-###-SSB = 40° D Soft Steel Back
LSL-###-SB = 80° D Steel Back
LSL-###-HSB = 90° D Hard Steel Back
LSL-###-HSBX = 90° D Hard Steel Back – Stamping (For Temperatures up to 350° C)
LSL-###-SHSB = 95° D Steel Back (DISCONTINUED)

For example it is confusing that the LSL-175-HSB is quoted as 95 Shore D on this web page:
but when you click on the details, they quote its hardness as 85 Durometer:
They claim that: “This plate material can be used as the basis of a mould when making rubber stamps.” That would make this plate a 90° D HSBX not HSB, since high heat is required to press the plate in to the matrix. The only difference between HSB and HSBX is that the HSBX has a Heat Resistant Adhesive Layer, but the polymer layer is identical. The HSBX is also suitable for some Hot Foil Stamping applications.

Confusing!!! One has to be a Detective to match the proper code to the proper plate.


Tokyo Ohka Kogyo was the original maker of Miraclon and Rigilon but a few years ago Jet took over manufacture; somehow Kodak got into the US distribution of it, and longtime distributors like Anderson-Vreeland and Gene Becker stopped selling Miraclon (one A-V rep blamed the Fukushima disaster for the change).
I see different designations in JetUSA and Kodak online information about Miraclon; Kodak uses the old TOK designations like Miraclon MS and DS and Rigilon MX (but no HX, and HX145 was my standard material). The Kodak Miraclon tops out at 80 degrees, but no numbers are given for the harder Rigilon molding plates. Also, the only Kodak plate listed in 145 thickness is Rigilon. Jet USA also calls their product Miraclon but uses entirely different designations as stated above. I also note JetUSA is selling “Miraclon” on eBay with “patent pending” on the label. This is all very confusing.
I haven’t needed any new HX since the change occurred, and it doesn’t seem to be available any longer; the MX might be OK but the great thing about HX was that it had a blue surface layer that gave a visible image, and could indicate a flaw that would be hard to spot on the all-yellow plates.

oh, yes!
Tokyo Ohka Kogyo Rigilon HX-145 were the plates I started out with almost 10 years ago. Nice green color and a matte finish ( they call it Digital Flat Top these days ) so it could hold more ink for the solids. They were hard as glass. Literally, shards were flying when I was breaking them on purpose. On a very few occasions, I “ping”, wiped off the isolated punctuation marks. They were so strong that you could practically push them through the paper. I was tempted to make male and female dies out of it for die cutting. And they did not require any special processing. I could make the plates with my eyes closed!
They could take a heat too. unfortunately I never got around to try them for foil stamping.
The dwindling rubber stamp market and the nuclear disaster brought their production to the end. I still have some small pieces left, and using them sparingly for finicky business card jobs.
I found a similar plate to it, from Flint, the WA240, the polymer is matte orange, but it is much softer. 79 deg. Shore D. Rigilon HX was quoted 90-95. I measured my leftover piece, it was right in the middle, around 93.

Anyone tried the photo-polymer plates from China?

interesting, the picture shows it green !


For the record, durometer measurements are not in degrees, they are dimensionless.

So, when manufacturers describe their press roller or photopolymer plate durometer with a number followed by a degree sign, what does the degree sign represent?

The degree sign doesn’t represent anything. I can only surmise that they don’t know durometer scales are dimensionless…..and I’m not trying to be a smarta— or know-it-all. In the following article, below the big table with all the durometer scales, read the second paragraph below the table:

The only degree reference in durometer that I know of is the angle at which the indenter (or “needle”) in the durometer gauge is beveled. The bottom of the indenter is in the shape of a frustum cone, which means a cone with its pointed tip cut off flat.

P.S. In that and some other articles, they say to take a measurement after 15 seconds (or after some period of time), after the indenter has had a chance to press into the material. However with printing rollers, which are measured on the Shore A scale, we were taught to take a reading immediately, and I believe all the roller manufacturers do this as well.

To degree or not to degree is not the question now. The question is what do those numbers represent.

My modest tests confirm, that they just take a Durometer, press it against the particular Photo-Polymer sheets’ surface and report the highest reading. The high number always looks better on the Sales Sheet than the low number.

I took the FlintGroup nyloprint data and plugged it in to Excel to visualise it. The attached image is not a scientific representation, just a layman’s attempt to visualise how hardness relates to the thickness of the material.

The printing plates correlate well. The moulding plates not as well, but there was fewer data about them. WA 240 is on its own. Could be a typo too.

So, if the nyloprint polymer would be tested 1/4” thick as suggested by the ASTM 2240 standard, it’s hardness would be only 30 Shore D ( 0s ). All those particular printing plates have the same polymer material. So their hardness is the same = 30.

The big difference in actual readings is caused by the so called anvil effect. On a thin substrate, the hardness of the base material drastically increases the apparent hardness reading of the measured sample. In the extreme case, the indenter will sink to the base material and stop there. The Durometer will become a Depth Gauge, showing extremely large values. Actually the durometer value has a dimension, it is the linear travel of the indenter. On the early models they used dial gauges to read the small movement of the indenter. Instead of 360 they divided the circle in to 100 divisions. So, calling it a degree is also correct.

So, when JetUSA says: LSL-###-HSB = 90° D
What do they mean?

The value is too hight to be a ASTM 2240 ( 0s ) value.
Not to mention the real value of ASTM 2240 ( 15s ).
They have a range of thickness’s. Which one is the 90?
To have all the thickness’s read at 90, they would have to reformulate the Polymer for each thickness. That is very unlikely!


image: anvil effect.JPG

anvil effect.JPG

I don’t know the answer to your question. Unless someone else on Briar press has a better idea, if I were you I would try to contact someone in a high enough technical position in a plate manufacturing company (as opposed to a plate distribution, sales and/or processing company). If you could bypass the sales and marketing people, that would help too. So, some of the choices you have for possible companies to contact are:

Miraclon plates made by Kodak, Rochester, NY

RB-Cor Miraclon and Rigilon plates made (or distributed?) by Econo Products, Rochester, NY

Nyloprint plates by Flint Group, made in Germany I think, but I could be wrong. (Flint Group bought the Nyloprint plate division from BASF some years ago).

Toyobo from Japan


The above link says they are “Partners in the Worldwide distribution…”, etc., but it doesn’t say they are manufacturers.

Unless I missed it, there doesn’t seem to be too much info on who actually makes the plates JET USA sells, or where they are made.

Did I forget any other manufacturers?

By the way Louie, that was an excellent bit of work you did above, in your study of plate thicknesses vs durometers. The way you put the data in Excel and added a trendline (which was basically to do a regression analysis on the data), made everything a lot more meaningful.

Than I started in Plate making, I simply tested every Plate out there, this let me to Metal backed as opposite to flexible,
I still constantly check and test Plates but have settled on Nyloprint as my house plate for the hardness it caries and the 4 pt type it can hold and Toyobo Printight for etching as they wipe without Plate Tone.
I make Film FM and plates up to 24 x 30.

hardness comparison of three different plates: HX-145, LSL-145 and the mystery plate I got a while back. the comparison is relative to the mystery plate, it’s value is 1 on all four charts.
the first chart shows the initial hardness. not much difference is visible in the values. the second chart shows the hardness after 15 can already see a greater difference between the three plates. the third chart shows the estimated hardness if the measurements were according to ASTM 2240. here you can see actually how they compare and feel in actual use. the fourth chart shows an approximated modulus of elasticity of these plates. very similar to the third chart.
the same material can be measured and represented in a different manner.


image: hardness.JPG


to answer my own original question, the plate manufacturer can not be identified just by looking at the plate.there are no markings on plates. so 10 sheets per case, for a hefty amount of money, one can only hope that he is getting what he ordered !
the Shore-D number alone does not help much either, unless it is quoted as it was obtained based on ASTM 2240 standard. or any other published testing agreement or standard. it is like the RGB numbers alone do not mean a lot, unless you know which RGB Colour Space they come from.



I know this might be off topic. I have just picked up a A4Ttc polimero plate machine. Looking for operating manual. I was told to ask here.