Best Watermark Detection?

I have never checked for a water mark as of yet but one ? I have is do you put the stamp with the front face down and put the Lighter fluid on the gum side facing up. You say this will not hurt the gum so you just let it sit there until it is dry before you pick it up .

I have never checked for a water mark as of yet but one ? I have is do you put the stamp with the front face down and put the Lighter fluid on the gum side facing up. You say this will not hurt the gum so you just let it sit there until it is dry before you pick it up .

lukusw,
I got your two full size scans via email, but still cannot correct these images into something meaningful. Some older scanners (EPSON being notorious) are set by default to produce images that use a non-standard color profile and just don't produce good scans into an 8 bit image.

You need to rescan your stamps AFTER adjusting your scanner's configuration.

You can find the instruction manual for your EPSON scanner here: https://www.epson.com/cgi-bin/Store...ortIndex.jsp?

This page might describe what you need to do: https://files.support.epson.com/htm.../custm_2.htm . Look for the "Color tab" section. The ICM (for Windows) or ColorSync (for Macintosh) radio button might allow you to choose "sRGB" instead of "EPSON sRGB".

I don't know exactly what is incorrectly happening, but something is causing your scans to be insufficient for use. If the above mentioned methods don't improve quality, then email me again and I'll help you via a remote assistance session.

Here is the same stamp, playing around with settings. Clarity was used for these tests. Ryan, I used your suggestion and changed the color settings from Epson default to ICM (using windows). The first photo is sRGB color setting at 600 DPI. The second is sRGB monitor color setting at 600 DPI. I'm not savvy enough with computers to know the difference between sRGB and sRGB monitor, but to my naked eye, I don't see a significant change. Ryan, I emailed you the full set in case you can do some magic on them.

Kingstonstamper,
You've got the basic idea correctly. Make sure that you do it in a black watermarking tray, bottom of a black ashtray, on a black piece of glass, etc.

The gum won't be hurt if you just let it dry in the tray or whatever you choose to use. You can gently use tongs and remove it from the tray and then place it on something like a paper towel to dry it faster. Watermarking fluid penetrates paper, but does not "wet" gum nor the paper of the stamp or something like a paper towel.

Treat it as gently as you would when dry when using tongs, and you will have no damage even when soaked in a watermarking fluid.

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Stampalotapus,
RetroReveal.org may be the same site that I was looking for earlier in this thread. I'll get a chance to confirm that later.

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Luke,
I got your sRGB full scans via email. Their color levels are more "correct", but they still are not as good as I hoped for. Here's your earlier Ronsonol scan next to my #416 Ronsonol scan from earlier in the thread. I did adjust the "levels" of your scan to bring out more contrast:



Note how your scan (and all of your others) has uninked paper color that is similar to the design areas. My image has very clear contrast between paper color and the design ink. Maybe yours has gum? Maybe your scanner's light source is different? Maybe you need to use much more watermarking fluid? Maybe your scanner setting are still not optimal? We can work on figuring out why in further email messages.

The red arrows on this image point to areas that could be portions of a Single Line watermark:



There are way too many variables for me to be sure, but that is my best educated guess given only wet scans of the back of your stamp. With the information that I do have, it appears to be a Single Line watermark "S" similar to this position:



This should conservatively depict the ink offset on the back of your stamp:



As for sRGB vs. "Monitor sRGB", the "Monitor sRGB" one was probably created when you performed a Windows "Calibrate Display". Windows has a "Wizard" tool that does help even without color calibration hardware. Or maybe you did at one time use color calibration hardware.

Regardless of how that color profile came to be, your "less wet" Clarity scan allows us to see the H in oval cancel on the front of the stamp quite clearly:



I'm actually amazed that your "Less Wet" Clarity fluid scan so clearly shows the cancel on the front. I'm starting to think that Clarity is unsuitable for general wet scanning. However, it could serve a good purpose for advanced watermark detection techniques such as creating an image mask to help eliminate cancels from contaminating other wet scanning watermarking data. Clarity fluid might have too high of an index of refraction. So far, Ronsonol seems superior for general wet scanning watermark detection.

Overall, there is obviously a need to better detail wet scanning technique through further experimentation.

For the next step in experimentation, please post dry scans of the front and back of your stamp. 600 dpi is sufficient. I'm enjoying trying to advance these methods of analysis!

Wow I have never thought of wet scanning, been using ronsol for years. Wish I had back some of the unsure stamps I sold for next to nothing.

Jim6092252,

Wet scanning is the way to go. Black and white or Greyscale is best. Once scanned, you can alter your image by viewing different tint variations (orange, red, blue, grey. etc); you can alter the degree of brightness; and you can alter the image size!

Jack Kelley

Historical DNA: Extremely valuable information and great explanations, especially with the arrows pointing out the marks on the stamp and the corresponding sample of watermarks. I might suggest, however, that the watermark that is closest to your example is the one in the grid two stamps above the stamp to which your arrow points.

All: this has been a very interesting discussion and one I will bookmark for future reference. Thank you!

Alan B.

i am going to try them all. a very big thankyou to everyone who replied

To my knowledge Clarity is non-toxic and non-flammable whereas Ronsonol (per OSHA) has hazardous qualities besides being flammable. It contains Naphtha which has been linked to kidney and nervous system issues and is absorbed through the skin. It may takes quite a bit of it to cause problems for most though.

Does a black light work to detect watermarks?

I did quick experiment with some Maylasian stamps. These have a POS watermark.

I scanned the stamp, then loaded it into Lightroom, just set Auto Tone (it was white), and I can spot the rounded watermarks. Scanner was set to gray scale. I will have to scan in color to play with color channels.





Yeah! I can usually spot the watermarks but less sure when they are not there and cancellations masking them. I tred SW and lW lights and no joy.

Are Malaysian stamp watermarks usually tough to spot? Have you tried this method with any of the US Washington / Franklins?

Not yet. I will try tomorrow. I was happy since I was checking these stamps this weekend and looking separating watermark and unwatermark varieties.

Well, I tried the same method of using the scanner to detect watermarks on a WF issue with a single line water mark with no luck.
I am not 100% sure I see the watermark with clarity wm fluid. I think I have a partial you in the lower left corner (viewed from back) but not sure. I need to find another sample. I did notice you get different results if you can with stamp against the white back ground on scanner cover or a black background since light can reflect back when using white background.