Hi, I am new to Stamporama, so not really sure if this is in the right place.
Having recently developed a renewed interest in collecting the Washington-Franklin series, I found I had difficulty in positively identifying those issues that were offset printed.
In looking for a solution I first used a research level metallurgical microscope. The breakthrough came when I used grazing illumination. The differences between printing techniques were striking.
With the acquisition of a USB connected digital microscope, I applied the same grazing illumination technique and found I could reliably tell an offset printed stamp from an engraved stamp. The microscope itself is an inexpensive one purchased from Amazon for less than $20.
Grazing illumination is that which is directed at the object from a very low angle. In my setup I use a small LED flashlight from Harbor Freight, although any small LED flashlight should work. Because I wanted a permanent setup, I remounted the microscope using some bits and pieces I had laying around, but the microscope can be used with the mount that comes with it Observations are made with the microscope’s internal LEDs turned off. The LED flashlight in the photo is on the left mounted at a small, nominally ten degrees, angle from the horizontal.
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Below are a couple of examples imaged by the USB digital microscope. Note the flat appearance of the offset printed example (red), and the 3D effect of the engraved example (green).
Because the USB digital microscope is operated via software in a personal computer it affords the ability to store permanent records of observations as jpg images which may be filed for later use. David Parsons, also a member of StampOrama, recently published an excellent paper on the general use of USB digital microscopes for stamp examination. To learn about additional uses I highly recommend it. http://www.renostamp.org/post_boy/articles/Using_USB_Microscope_for_Stamp_Identification.pdf
I have one as well, and it is one of my favorite tools for my collection. The "grazing" technique works well for imaging watermarks in fluid as well. It also takes the best pics of tagging I have seen.
That is a very clever idea. I have also done that with a less elaborate set up.
I'll try to build something like yours and maybe add a slight enhancement and
add a voltage regulator power supply for the LED diode light source.
If you want to try on your own here is some schematics and text on theory of
operation:
All you really need is some phenolic perf board, a few discrete components;
diodes; capacitors; resistors; an IC regulator etc. You will need some solder,
and a soldering iron too.
Most of those can be had from Radio Shack. However I usually buy better
quality components from a large mail order firm. They will probably have a $25
minimum. But I can usually find some other neat stuff, if I get my hands on
their paper catalog.
If you want to try the watermark thing, try different color LEDs. I've read in
another thread that some had better results with different colors.
Thank you for posting this. I've heard many schemes for detecting engraving,
including placing Reynolds Wrap on stamp and rubbing to get an impression
of the raised ink. Finally somebody has hit a out-of-the-park HOME RUN and
come up with something that really makes sense.
Thanks for the suggestions and the website. I may give the power supply a go, and will be giving the watermark technique a try with different colored LEDs very soon.
The least I could do for such a great idea as that.
If the link I gave you doesn't have enough detail, like how many ohms are the resistors, or how many
microfarads are the capacitors, there are lots of circuit diagrams available. Just Google something like
"variable power supplies using voltage regulator ICs". That should give you tons of schematics with
specific component values and save you doing all the experimentation.
Have fun with it and share with us too....
TuskenRaider
I guess I'm lazy. I just use a Durland catalog to determine which plates were used to produce offset 3rd Bureau stamps. That not only identifies the press, but the Type as well:
Those plate numbers act like little certificates of authenticity!
Lars
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"Expanding your knowledge faster than your collection can save you a few bucks."
The link to David Parsons, on the excellent paper on the general use of USB digital microscopes for stamp examination did not work for me. Anyone else have this trouble?
I did give it a try this afternoon after repositioning the microscope so I could see almost an entire stamp. Using the grazing illumination on a stamp wetted with Ronsonol as noted by Seanpashby above certainly enhances the watermark...at least in this case.
I am curious....in the first picture you posted, the microscope doesn't look anything like mine or the one in the amazon link you posted. Have you modified it somehow?
I have found the easiest way to differentiate between the offset and engraved printings is by feel. The offset has a smooth finish and the engraved have a raised feel to the printing. The offset also have a blurry look to them. Now for the types i found the USB microscope works well. I also have a hands-free image scanner. http://www.averusa.com/classroom-te...b350plus.asp I found mine on ebay for $100.00 plus shipping. It is larger and bulky but I get great images. When i get a chance I will post some scans of stamps I made with it.
I built my own stand by mounting it on a flexible gooseneck from a broken magnifying glass and a large wooden base. This way I can spread out a lot of stamps. The amber thing is an old pill bottle with bottom cut out and sanded smooth. By unmounting the scope and placing the tube on it, you can use it as a "hand held" for looking at stamps mounted in albums or anything else that won't fit under the mount.
No, the microscope itself isn't modified, but I did put together a junk box mount for it. I wanted something rigid but adjustable so used an old microscope focusing block and tube. The microscope slips down into the tube.
Seems to work pretty well. I think I am going to do something similar as gslaten did.
I have my (non-functioning) microscope from when I was a kid. It was a cheap Tower brand sold by Sears. I think I will see if it will work to hold the electronic unit. I really like the idea of the fine-tuning adjustment option and the potential steadiness of the setup.
"Musicman: Do they not have people who do research on these things???"
Sure they do. But, they are counting on suckering customers who do not. If only 1 in 5 potential buyers is fooled into buying it, they still make money by charging 7 times its nominal value.
Just a heads-up about security of the software on the disk that came with this incarnation of the product. When installing the driver, my security software detected the IDP.ALEXA.51 trojan. The detection may be a false positive, but I proceeded with caution and did not install the Driver or the software on the disk.
Its probably nothing, but you can read the link below for more info. If your browser search gets hijacked, that would be a sign it was not a false positive.
As an alternative I simply let Windows install a USB video driver and then downloaded the "Plugable Digital Viewer" from here (though any camera/video software would probably work), although that is not the model I purchased. I should have purchased the "Plugable" branded one.
Anyhow, the stand and such are pitifully bad (as previous posts have suggested). I see there are other versions of this that have better mounts. Might be worth spending a bit more to get one of those.
Lewis, you surely did right by not installing that software. The microscope that you bought is the exact same one sold by plugable, which is what I bought. My guess is that they are made in bulk by a manufacturer, and sold to numerous vendors that add their own software and package. They now sell just the stand/mount for it, with a gooseneck or rigid stand.