seigaku
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Post by seigaku on May 11, 2018 15:16:51 GMT
I expect this post to generate some controversy, but here goes anyway!
Watermark detection is one of the major headaches in philately. That goes doubly so for some of the Latin American countries I enjoy collecting--for example, Argentina, Brazil, and Mexico. Lacking a Signoscope, I was very fond of my long-dead Morley-Bright Roll-a-Tector when I was faced with many hundreds of stamps needing watermark ID. Many people seem to dislike or distrust the Roll-a-tector, but it worked well for me for decades without mishap, and avoided the noxious fumes from watermark/lighter fluid. These Roll-a-Tectors are no longer made. The sachets have a limited shelf-life, so replacement parts are now rare and unreliable.
I have been experimenting with a possible home-made DIY watermark detector using the same approach. Warning--this is experimental and is not safe for stamps.
The Roll-a-Tector sachet contains a viscous colored goop contained in a thin but strong, sealed plastic bag. The bag is placed over the stamp and a roller is run over the top until most of the goop is forced away from the stamp, leaving a little extra goop in the paper depressions forming the watermark.
I cut two pieces of plastic sheeting (I used painters' drop cloth) and put a drop of caulking between them. I put a stamp underneath and rolled out the caulking--and was able to see the watermark! So this is now at the proof-of-principle stage.
Here are some thoughts:
--This is a disposable watermark detector and may be useful only for a short time, probably less than a day.
--The plastic needs to be strong enough to protect the stamp and flexible enough to reveal the watermark
--The caulking should be as dark as possible in order to maximize visibility of the thin remainder of caulking that shows the watermark
--The base under the stamp should be hard, and as smooth as possible
I am hoping this catches a few people's interest enough to try it, and we can compare notes on what works and what doesn't work--and ultimately whether some variant of this approach could be a safe and useful addition to our kit of tools.
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Beryllium Guy
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Post by Beryllium Guy on May 11, 2018 20:40:54 GMT
I expect this post to generate some controversy, but here goes anyway! Here are some thoughts: --This is a disposable watermark detector and may be useful only for a short time, probably less than a day. --The plastic needs to be strong enough to protect the stamp and flexible enough to reveal the watermark --The caulking should be as dark as possible in order to maximize visibility of the thin remainder of caulking that shows the watermark --The base under the stamp should be hard, and as smooth as possible I am hoping this catches a few people's interest enough to try it, and we can compare notes on what works and what doesn't work--and ultimately whether some variant of this approach could be a safe and useful addition to our kit of tools. Thanks for starting this thread, Alec. It is interesting stuff indeed, although I am not sure about the controversy part. All I can say about that is that in the year and a half that I have been on TSF, the group always seems to embrace controversy rather than avoid it. I, for one, am not at all familiar with the Roll-o-Tector equipment, so I did a web search to try to see what it looks like, and I think that I have a better idea now. For me, the first and simplest watermark detector is a strong light source. I have been able to use my desk lamp in one of two modes: my first attempt is simply to hold the stamp up to the light source, usually printed side toward the lamp, and look for the watermark. This works best for unused stamps without hinge remnants. It also works on used stamps, as long as the postmark is not too heavy, so as to effectively make the watermark unreadable. If this technique does not work, then I hold the stamp face down under the strong light source with a dark background underneath it--sometimes that will bring out the watermark. I estimate that one of these two light source techniques works about 60-70% of the time. If using the light does not do the trick, then I will use watermark fluid and a detector. If that doesn't work, then I can try submersing the stamp in water, provided, of course, that it is not unused with gum which needs to be preserved. As I am now in France and without the vast majority of my stamps, I am not in a position to do any experiments myself, but I will follow with interest whatever you and others will continue to post on this thread. |
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tomiseksj
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Post by tomiseksj on May 11, 2018 21:44:56 GMT
Alec ( seigaku ), I purchased a Roll-a-Tector several years ago to try to determine watermarks on stamps on cover but had only limited success. If you're going to pursue this experimentation, you might consider using a small zip lock bag to contain caulk, rather than plastic sheeting. In addition to providing a greater measure of protection for the stamp, this might also extend the usability of the material by slowing its drying time. Like Chris ( Beryllium Guy ), I'd be interested in learning how your experiment is progressing. |
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seigaku
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Post by seigaku on May 11, 2018 22:57:48 GMT
Thanks for the responses! I say "controversial" because some of my friends feel that the Roll-a-Tector risked damaging the stamps (apparently with known cases), and if so, my crude DIY scheme logically must be far more dangerous.
I agree that a strong light source is the first resort, especially if the issue is a simple decision of watermarked vs. not.
But it can get more complicated: In my Latin American stamps the same image may have been printed on papers with 3 or 4 different watermarks, and catalogs like Scott lump roughly similar watermarks such as Argentina Wmk. 90. The caption under the illustration of Wmk 90 says "In 1928 the watermark R. A. in Sun (90) was slightly modified, making the diameter of the Sun 9mm. instead of 10mm. Several types of this watermark exist." As another example, in Mexican stamps there are 4 different known kinds of the CORREOS MEXICO watermark which are not distinguished (or even mentioned) by Scott. There are kooks like me who enjoy trying to understand those subtle differences! (It is certainly not for everybody)
One nice thing about the Roll-a-Tector was that the image remained visible in the sachet for as long as the user required. This allowed further consideration of the image, including various size and distance measurements. That is one of the main reasons I am messing around with this DIY approach. Another benefit of the Roll-a-Tector approach is that it has moderate success reading watermarks of stamps that are still on piece!
The idea of using a baggie is brilliant! I was trying to think of what kind of plastic to use, and a conventional sandwich bag comes close to my ideal image of strength and flexibility. Having a zip-lock seal is a great addition. I only use a small quantity of caulk, about the size of a pencil eraser, but even that small amount needs to be watched carefully.
So thanks again for the feedback. I am not sure how actively I will be pursuing this, but I will keep you posted.
--Alec
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Post by Bas S Warwick on May 12, 2018 2:02:36 GMT
Is that caulking the same material in a tube we call 'mastic in UK/NZ
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seigaku
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Post by seigaku on May 12, 2018 4:29:23 GMT
I expect it is the same, but I don't know the UK/NZ jargon. It is the kind of goop we spread around the rim of a sink or bathtub, or possibly use to plug up small holes. The need is for it to fill in the microscopic depressions in the plastic lying on top of the watermark (which is a slight depression in the surface of the stamp).
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scb
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Post by scb on May 12, 2018 6:41:57 GMT
Interesting... I've experimented with similar idea (as I've got a dead Morley-Bright that I am kind of fond off). What has held me back is that I would like easy, solid and durable pouch (i.e. something similar to original). I've played with zip bags etc. but they are too "soft" for long term use. But your idea of using "heavy duty" cloth sounds something that could work.... One could melt/seal the edges with hot iron as final step. As for gel... I've been playing with various transparent gels (cosmetic/healthcare) to which I've mixed a drop of dark blue ink. Toothpaste works best  But you really have to be careful how much you use it (about size of pea seems to work). Replacing the ink with some water soluble pigment might be a smart idea, as ink can get bit messy. -k- |
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seigaku
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Post by seigaku on May 12, 2018 14:09:35 GMT
Thanks for sharing, k
First thing this morning I tried a zip-lock bag and toothpaste (both white and gel), unfortunately with negative results. The plastic of the zip-lock bag seems to be too hard--strongly wanting to maintain a flat shape, so it won't deform to match the surface of the stamp. Toothpaste is not viscous enough to deform the plastic. Toothpaste should pose low risk of damage to the stamp--which is testable if we go that way. Adding pigment to the toothpaste should increase visibility, but decrease stamp safety (Hmmm--anybody remember the trick black toothpaste long ago advertised in the back of comic books?).
Both bags and toothpaste are still under consideration, but the present combination isn't effective. Either I need to increase the viscosity of the gel/paste, or decrease the hardness of the plastic. There are other brands yet to be tried.
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tomiseksj
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Post by tomiseksj on May 12, 2018 14:37:21 GMT
...The plastic of the zip-lock bag seems to be too hard--strongly wanting to maintain a flat shape, so it won't deform to match the surface of the stamp... I've got a small (3"x4") bag that appears more pliable than the standard freezer bag as well as the plastic of the original M-B sachet. Send me a PM with your mailing address and I'll send it to you. |
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Beryllium Guy
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Post by Beryllium Guy on May 12, 2018 14:43:03 GMT
First thing this morning I tried a zip-lock bag and toothpaste (both white and gel), unfortunately with negative results. The plastic of the zip-lock bag seems to be too hard--strongly wanting to maintain a flat shape, so it won't deform to match the surface of the stamp. Toothpaste is not viscous enough to deform the plastic. Toothpaste should pose low risk of damage to the stamp--which is testable if we go that way. Adding pigment to the toothpaste should increase visibility, but decrease stamp safety (Hmmm--anybody remember the trick black toothpaste long ago advertised in the back of comic books?). Both bags and toothpaste are still under consideration, but the present combination isn't effective. Either I need to increase the viscosity of the gel/paste, or decrease the hardness of the plastic. There are other brands yet to be tried. Thanks for the added info, Alec. With each new post, I am gaining a better understanding of the challenge you are trying to address. Based on these last comments, I do not have much experience comparing the viscosities of various substances like caulk or toothpaste, so not sure that I can add much there, but I do use Zip-Loc and Zip-Loc type bags frequently for both philatelic and other purposes. They are great, for example, for shipping stamps in such a way as to ensure that nothing inside will be damaged by moisture, although as you pointed out in another thread, I think, they are not good for long-term storage as they will lock moisture in, too. Anyway, some comments about the thinness of the Zip-Loc material: 1) be sure that you are not using a freezer bag, as those are definitely much thicker plastic than bags not intended for freezing, and 2) in my experience, the smaller the size of the bag, the thinner the material, so use a "snack" size rather than sandwich or quart or larger, and 3) last but not least, if you are trying to get the thinnest possible plastic, buy the least expensive / generic / store brand of bags rather than the brand name Zip-Loc. I think that these less expensive brands will tend to have thinner plastic which is how they can reduce cost and offer a lower price. Well, I don't know if any of that helped, but I hope so, perhaps in some small way. Good luck with your trials! Edit: Just saw Steve's post, as he was writing his at the same time I was writing mine. Yes, a 3" x 4" bag should be the snack size I was talking about. You can buy a box of them at the supermarket for less than a dollar, I think. |
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seigaku
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Post by seigaku on May 12, 2018 16:23:21 GMT
Yes, I think the smaller size and cheaper construction are the way to go. I suspect that a simple test might be whether the bag make a "crinkle" sound when it is crumpled--that sound would indicate an undesirable stiffness--and we are looking for plastic that stays relatively quiet (obviously, this needs to be tested and calibrated).
Steve--I am not quite to 50 posts (getting close), so I am not sure whether sending the bag is legal yet. But I won't complain if you accidentally fill it with stamps (preferably used Latin America). And I won't return it full of caulking.
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tomiseksj
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Post by tomiseksj on May 12, 2018 17:24:05 GMT
...Steve--I am not quite to 50 posts (getting close), so I am not sure whether sending the bag is legal yet. But I won't complain if you accidentally fill it with stamps (preferably used Latin America). And I won't return it full of caulking. If you don't tell Admin, neither will I. |
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seigaku
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Post by seigaku on May 12, 2018 19:31:07 GMT
Just a quick update. I tried a Ziploc "snack bag" made of relatively thin plastic with some success. Caulking worked better than toothpaste, and I was able to lift a few watermarks, but have yet to be able to image a whole stamp. Although the thinner plastic allowed the watermark to show, I found that after very few applications the plastic developed permanent creases that conflicted with the watermark images.
Morley-Bright also made a related device called the Inst-a-Tector, where the sachet was pressed against the stamp rather than rolled against it. I have never used one, but I simulated the Inst-a-Tector by pressing my bag against the stamp with a piece of glass I could see through (the old base of my Roll-a-Tector). This seems to work better with toothpaste, suggesting that a somewhat lower viscosity may be better for pressing, as opposed to rolling.
I am about to go to the hardware store, hoping to buy some black caulk/mastik. A darker color should help. I am also thinking about trying a tube of ready-made cake frosting. This whole reverse-engineering experiment gives me a better appreciation for the original engineering and fine-tuning that went into the old device.
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scb
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Post by scb on May 13, 2018 7:47:42 GMT
Yep. I mean the base philosophy behind it is very simple, but trying to recreate it is painful.... This is how I've "reverse engineered" in my head. Watermarks are thinner than other areas of the stamp, bit like bumps on flat surface. When you press/roll/push on top of the stamp, the plastic has to be "elastic" enough to adapt into those microscopic bumps, but also elastic enough to eventually raise back up to original shape (I think this is where zipbags etc fail, at least my MB sachet feels bit like "raincoat"). Now enter gravity, which allows the remaining gel to flow and fill the bumbs on the bottom (but if the gel is too sticky it will not flow)... And voila, you should have image of watermark.
In a way this is not much different from using kitchen foil & rubber for detecting whether or not stamp is engraved.
-k-
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seigaku
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Post by seigaku on May 13, 2018 13:38:52 GMT
Thanks Keijo--
Is there an available write-up somewhere about the kitchen foil engraving detector? Or could you say a little more about it?
--Alec
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seigaku
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Post by seigaku on May 13, 2018 15:12:52 GMT
Here is another update. I went to the hardware store and purchased a tube of "Dap" brand black acrylic latex in the hope that the black coloration would improve visibility of the watermarks. It was a big improvement! I got equally good results from both the thin "snack" bag and the slightly thicker "sandwich" Ziploc bags. The images are often crisp, and quality of results is now approaching that of the original watermark detector.
However I have now encountered a new limitation. The bag+caulk appears to be good for 10 to 20 usages before the caulk stops adhering to the plastic, at which point the image stops being retained and it no longer works. I suspect that it may be due to loss of a volatile "stickiness" component in the caulk. This may even be a good thing--it reduces the chances that I will wear out the bag and destroy a stamp.
Now I will be saving various plastic packaging bags from commercial products for comparison testing.
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Jerry B
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Post by Jerry B on May 13, 2018 15:15:00 GMT
Hi
The major problem with the Roll-A-Tector was the sachet breaking and ruining the stamp. I know of someone to which this happened. So, be careful.
Jerry B
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seigaku
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Post by seigaku on May 13, 2018 16:09:14 GMT
Thanks for the warning, Jerry, and that is why I put "Dangerous" in the title of the thread.
However, watermark fluid also could pose a risk to the user if not so much to the stamp. We are not given any information on the chemical composition of either watermark fluid or lighter fluid.
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seigaku
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Post by seigaku on May 13, 2018 16:22:26 GMT
Oops! I fumbled a key and the draft message posted itself. Continuing...
I remember long ago reading that standard "safe" watermark fluid might be cyclohexane. If so, it evaporates very fast (as we know from experience) and concentrations in the air can quickly exceed safe limits. Safety information for cyclohexane says, in effect, don't trust your nose. Lighter fluid is less volatile, but again, we don't know what it is and we are not using it for its intended purpose.
I am not trying to argue pro or con, but people should be aware that there are risks of various sorts, and we should be careful.
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scb
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Post by scb on May 13, 2018 18:24:48 GMT
1. Take a piece of kitchen (aluminium) foil
2. place it on top of stamp that you want to test (engraved or not)
3. Gently rub the foil on top of the stamp with eraser (or similar soft unit) at least 5-6 times, and at least until you see the stamps outlines(teeth) coming out.
4. Flip the foil... If the stamp is engraved, you'll see a mirrored image of engraved parts transferred to foil.
And if the stamp is offset-litho or other flat surface printing, all you see is outlines/teeth of the stamp.
This trick has got 100% success rate.
-k-
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seigaku
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Post by seigaku on May 13, 2018 19:56:44 GMT
That is useful! Hmm, now I have to eat a bunch of chocolate bars in order to have a sufficient supply of foil.
I probably shouldn't ask a question that I can answer just by trying it, but for the public record, how does the foil method respond to typography? Typo vs litho printings are sometimes important, such as in Argentina. Is there enough relief to register in the foil?
PS This is my 50th post. Hooray!
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scb
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Post by scb on May 14, 2018 4:59:53 GMT
seigaku .... Usually both litho and typo respond the same way (no transferred relief)... Possibly the best telltale of typo stamp are protruding edges (with offset/litho edges are straight). I've showed the below image on my website time and again as example of litho (left) vs. typo (right). Sometimes you'll see the difference without any tools, sometimes you need a magnifier/microscope to have a proper look. 
-k-
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mikeclevenger
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Post by mikeclevenger on May 14, 2018 13:05:08 GMT
Hey, well I use a Signoscope. A signascope is simply a very thick piece of Lexan (Plexiglass) with a silvery piece of metal under it. The signascope has a press, that smashes the stamp between the lexan and the metal and has a very bright light shining in from the end. You may be able to make one by stacking 2 -3 pieces of heavy plexiglass together, a piece of metal behind it, and clamp on each side of stamp with the likes of a few pair of c-clamps or even using C clamp vice grips may work better. Then shine a very bright light into the end. This should show any watermark it may have. If you are using thin sheet metal, you will have to put something thick and strong behind it to support the pressure needed to show the watermark. Also, some times less pressure is better on showing some watermarks. Just a thought? Mike.
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seigaku
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Post by seigaku on May 14, 2018 13:51:56 GMT
Thanks, Mike--That sounds quite do-able. I had no idea they were that simple. I will keep my eyes open to acquire the pieces, and hope to give it a try sometime. --Alec
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scb
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Post by scb on May 15, 2018 6:09:48 GMT
There are actually several (somewhat old) discussions of "DIY Signascope" on German forums (see for example www.philaseiten.de/cgi-bin/index.pl?F=1&CP=5&ST=2645&full=1). Some say they've actually build working one for about 30€ of equipment costs. It's been on my 'try this during the summer' list for years (and always postponed due to other things). -k- |
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seigaku
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Post by seigaku on May 15, 2018 20:02:58 GMT
Thanks for the link, Keijo--I skimmed that thread, and it seems worth studying more closely.
I would like to ask anyone with s Signoscope and a Roll-a-tector (even if it is dead) to try a little experiment with a few stamps: First look at the watermark with the Signoscope, then roll the stamp a few times with the Roll-a-tector, and re-examine it with the Signoscope. Does rolling the stamp improve the watermark image in the Signoscope? I often get the impression that a watermark becomes more visible to the unaided eye after the stamp has been "rolled" but wasn't sure if it might be that I just had a better idea of what to look for. Perhaps this experiment could answer the question.
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But you really have to be careful how much you use it (about size of pea seems to work). Replacing the ink with some water soluble pigment might be a smart idea, as ink can get bit messy.
