Author Topic: Article on How to Spot fakes and antique restoration with black light  (Read 303 times)

Offline rfkimba

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Hi Collectors,
I ran across this  informational tidbit  on the AntiqueAdvertising.com website  .

"How to spot fakes and antique restoration with black light


"Unfortunately, although most antique dealers and collectors are honest, you always have to keep an eye out for fakes, reproductions and antique restoration when buying. As time has passed, the forgeries have gotten better and better while many of our eyes of gotten worse and worse. Aside from using only REPUTABLE DEALERS AND AUCTIONEERS, your best bet is to familiarize yourself with a black light and a few basic techniques to detect any potential problems. The Ultra Violet or “UV” light that is emitted cause many substances to fluoresce and reveal areas or materials that aren’t original to the piece. These techniques work on a wide range of materials and should be your go to when purchasing antiques.
Porcelain
When purchasing a piece of porcelain, especially porcelain signs, you should ask the dealer if you could take it into a darkened area for examination. Although the sign may look right to the eye, a black light never lies. When exposed to this light, the color of the antique restoration will glow a distinctly different color than the rest of the porcelain and quickly help you detect any antique restoration or touch-up. As a general rule, the harder the porcelain paste, the darker the color under a black light with hard paste turning a deep purple/blue and softer pastes appearing almost white."
 
Does anyone have any thoughts on the value of the use of this light for porcelain sign collectors? 
Thanks,
Bob Farber

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #1 on: October 22, 2017, 05:18:17 AM »
That really makes a lot of sense. And the cost of a portable, hand held UV light source is a lot less than I expected it to be. Here is one, of many available on eBay, from a US seller for $7.69 with free shipping (requires 4 AA batteries not included).

     https://www.ebay.com/itm/6-Inch-Portable-Handheld-UV-Black-Light-Torch-Portable-Blacklight-With-LED-USA-/202086615735

Description states:


    Check for counterfeit money, stains, hotel room cleanliness & much more!
    See UV hand stamps, UV body paint, antique glass & scorpions
    Has both a 4W UV bulb & also a torchlight.
    Compact, portable, battery operated (Not included 4x AA)
    Has a handy nylon carrying cord
    Material:plastic
    Color:black
    Size: 16.2×5.6×2.2cm/6.3×2.2×0.9 inches


Having been young in the 60s, I remember when "black lights" were the thing to have (4' fluorescent tubes were great) and the way they illuminated things in a group setting. I can see how this would make a restored patch illuminate differently than the original material, in more than just porcelain signs.

But with the cost of these signs being high, this would be a great tool to check for restoration or repair. Photos of such "discoveries" would be interesting. Not sure if it would result in a lower price at a store but if it works for this, it would say a lot about the history of the sign.
            John . . .

              

Offline Dan/Panther

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #2 on: October 22, 2017, 11:24:35 AM »
I have two of the lights John posted a link for. They work quite well, but are a little fragile. But what can you expect for $7.00. Still a great deal.

D/P

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Offline Sargeguy

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #3 on: October 22, 2017, 12:18:26 PM »
I have a fairly expensive UV light that produces both long wave and short wave UV. It is used for detecting fluorescence in minerals.  I just checked the N.E.T.&T. die-cut I just had restored and there was no evidence of fluorescence.  While this method may detect some restoration work, it cannot assure that no work has been done. 
Greg Sargeant
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Offline jsowers

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #4 on: October 22, 2017, 12:45:04 PM »
Not sign-related, but UV and antique related, and just as an aside--I also collect Fostoria American crystal. It was made up to 100 years ago and reproduced in the 1980s and 90s after Fostoria went out of business. The old crystal fluoresces yellow under black light and the new does not, so I have one to tell if what I get is the real thing. It's amazing to see the yellow glow from the old crystal and you do have to do it in a dark room. I have a GE electric black light that just plugs into the wall and has a switch and it works well. I first started with a black light CFL (compact fluorescent spiral bulb) and it didn't put out enough light, but the GE, which is about 18" long, works great and seems to be very sturdy. I can't find it online anywhere now, but there are others like it.

They also make LED blacklight flashlights with large lenses that look fairly sturdy that you could take to an auction. They're also used to locate pet stains, bedbugs and scorpions (yuck).
Jonathan

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #5 on: October 22, 2017, 03:08:42 PM »
The science behind this is the high energy UV light is captured by electrons in the atoms and bonds between atoms that make up the item, it excites the outer shell or the bond if you will, and since the electrons can not stay excited, when the electrons drop back into their normal shell, they give off the energy difference between the excited and normal states ( it it takes 1 unit of UV to excite the atom and only .9 units are given off when it drops back to normal, the .1 units will be exciting energy and the the .9 emitted light will be the change from UV to yellow as seen by the eye). That light is the energy of the UV light less the energy used up to excite the electron so the wavelength of the light emitted when the electron drops back to normal is longer than the original UV blueish and the typical fluorescence light will be in the yellow wavelength visible range.

Any atoms or even molecules that absorb UV light will fluoresce yellowish, look yellow and brighter since the eye sees yellow better than it does the high energy UV light. The emitted light will never be more blue than the UV used to excite the material.

Want to see something cool? Dissolve a multivitamin or a Vitamin B capsule in water and expose it to UV light. That's the vitamin before excretion as noted above as urine stains on materials.

Fluorescence is a laboratory tool to determine chemicals. They use scanning fluorescence instruments to scan through the spectrum to determine the exact wavelengths given off by the material under test and the resulting plotted spectrum is unique to the chemical or mixture. Teeth are very bright yellowish. Many applications of this and having both the don't look at UV and lower UV light source gives added capabilities.

But almost everyone knows this so posted for those who don't have a chemistry background.

If a porcelain sign is well restored using the same materials used to make the sign originally, the "fix" will not be seen, both the original and fixed areas will fluoresce the same.  This only points out differences in materials or areas being tested, not when or how.
            John . . .

              

Offline rfkimba

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #6 on: October 22, 2017, 08:50:02 PM »
Hi Collectors,
I'm posting this for Greg's feedback:
 If your beautifully  restored NET&T diecut
shows no difference in flourescence between old and added porcelain how can a collector know during a transaction it was a restored item of  possibly lesser or different value if it is not disclosed?
The only difference I noted on the before and after photos of the restoration  were porcelain areas on the reverse edge where rust was removed and porcelain added.
For comparison a badly worn nickel plated candlestick when renicked nicely commands a significantly higher price than the original. What  are your thoughts on restored sign valuation?
Thanks for your insights.
Bob Farber

Offline Sargeguy

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #7 on: October 22, 2017, 09:34:15 PM »
I'm not sure how it effects value.  I suppose it depends upon the amount of work done.  I assume minor repairs would not adversely affect value too much.  One sign I had restored needed greater than 50% repaired.  The NET&T sign required less.  I have another that only needed minor repair to be perfect.  I plan on disclosing all repair work I had done if I do sell.  Restoration is expensive( and it is not getting any cheaper).  When calculating whether a sign is worth repairing, I add the price I paid to the cost of restoration, if that equals 50% or less of the signs value, I consider it a good candidate for restoration.
Greg Sargeant
Providence, RI
TCI /ATCA #4409

Offline 19and41

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #8 on: October 31, 2017, 05:30:12 PM »
I have a small end firing LED UV light that I use in finding coolant leaks in vehicles.  It runs on 3 AAA cells and it, like me, was quite cheap.
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke

Offline HarrySmith

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #9 on: October 31, 2017, 06:20:47 PM »
I'm not sure how it effects value.  I suppose it depends upon the amount of work done.  I assume minor repairs would not adversely affect value too much.  One sign I had restored needed greater than 50% repaired.  The NET&T sign required less.  I have another that only needed minor repair to be perfect.  I plan on disclosing all repair work I had done if I do sell.  Restoration is expensive( and it is not getting any cheaper).  When calculating whether a sign is worth repairing, I add the price I paid to the cost of restoration, if that equals 50% or less of the signs value, I consider it a good candidate for restoration.

How do you determine the value of a sign?
Harry Smith
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Offline rfkimba

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #10 on: October 31, 2017, 10:27:34 PM »
Hi Greg,
When you state 50% of a "signs value  do you mean the sign value if it were in mint condition?
So a restored sign value(acquisition cost &repair cost) cannot be more than half of what that sign would be mint?
Thanks
Bob Farber

Offline Sargeguy

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #11 on: October 31, 2017, 10:31:28 PM »
Bob Alexander's price guide is the only reference that gives prices for signs.  It is not definitive, but can help give relative value of a sign compared to others.  Past sales on eBay are a good indicator for common signs that have sold recently.  I try to list prices on the Bell System Sign Types post that is pinned to the top of this board whenever possible. Condition is very important, probably more so than rarity.  If you are a novice who is interested in a sign it is a good idea to ask another collector's opinion.
Greg Sargeant
Providence, RI
TCI /ATCA #4409

Offline Sargeguy

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #12 on: October 31, 2017, 10:35:19 PM »
Hi Greg,
When you state 50% of a "signs value  do you mean the sign value if it were in mint condition?
So a restored sign value(acquisition cost &repair cost) cannot be more than half of what that sign would be mint?
Thanks
Bob Farber

That's my rule of thumb for a major restoration, I think I got that from discussion of oil and gas signs somewhere.   I don't have any examples of restored telephone signs that sold.  I think it depends upon the extent of the restoration, but a "survivor" sign will always be worth more than a restored one.
Greg Sargeant
Providence, RI
TCI /ATCA #4409

Offline rfkimba

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #13 on: November 01, 2017, 01:03:20 AM »
Greg,
WRT to restored sign value :
In the good reference book  dated 1999 "Encyclopedia of Porcelain Enamel Advertising" by Michael Bruner on p8 there is a half page discussion on repaired signs and their value. He indicates if " on average , though, a sign  had a quality  repair job would be worth at least 60 to 75 percent of what the sign would have been worth in mint condition with no repairs." . He lists dated  pricing of high quality  porcelain signs in this book including some phone signs.

Offline Sargeguy

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Re: Article on How to Spot fakes and antique restoration with black light
« Reply #14 on: November 01, 2017, 10:44:47 AM »
That's good to know-I will alert the wife!!!
Greg Sargeant
Providence, RI
TCI /ATCA #4409