Using an Ultrasonic Thickness Gauge to Test a Real and Fake 100oz Engelhard Silver Bar
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- čas přidán 23. 11. 2010
- Shows you how to use an ultrasonic thickness gauge to help determine whether a silver bar is real or not. It is one of the most accurate ways of determining if a bar is fake.
An ultrasonic thickness gauge measures how long it takes sound to travel through a material. Although lead and silver are very close in density, sound travels through them at very different rates (3,650m/s for silver versus 2,160m/s for lead).
By telling the UTG that we are measuing silver, it will show us how thick the bar should be if it is really made of silver. If that matches the real thickness, we have a real silver bar. Check the video to see how the results differ for the real silver bar and the fake one.
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The one we got was TM-8811, which I believe came from Amazon. Just about any UTG should work fine; it doesn't even need to be highly accurate (if it is accurate enough for just about any other applications, it's fine). You'll need to be able to either enter in 'silver' or the velocity of sound in silver (3,650M/s), but every UTG should let you do that.
Specifically, the change in the complex impedance at the interface causes some of the wave to be reflected back.
@monishdragon Yes, that is the type of application that the UTGs were originally designed for. The one catch is that you would need to be certain of the material that is used to make the cylinders (or, test on a part of the metal where both sides were exposed, if any).
The sound waves will bounce when they hit a material that has a different velocity of sound. So if there is lead in the middle of a silver bar, it would bounce off the lead. If you put a silver bar on a wooden desk, the waves will bounce back once they hit the desk.
@Begbucks The UTG should detect all fake silver bars. We have been unable so far to obtain a sample lead-filled bar, so we cannot say for certain exactly what the results would be. However, we cannot see how you would get a correct reading unless you tested in a location on the bar where it was pure silver straight through. Testing in the very center of the bar, however, would guarantee that it would not be pure silver straight through if it were one of the 2 types of lead-filled bars.
Once, again, this is incredibly useful information. thanks!
@PreciousMetalinvest We recently tried using the UTG on 1oz silver coins, but were unable to get a good reading (since there was not a large enough flat area on the coin). The probe (which is about 5mm wide, or about 3/16") needs to be on a completely flat surface to be able to get a reading. Most silver bars have such a surface, but coins do not. The velocities for various metals can be found fairly easily (e.g. searching for 'velocity of sound silver').
@milanolarry It is possible that it cannot get a good reading. That could happen if the surface of the bar is not flat, or is at a bit of an angle.
This would also work great on a tungsten-filled gold bar. Tungsten propagates sound waves at a MUCH higher speed than gold does so with a tungsten-core bar, the thickness reading would be way off. There are dealers who have bought fake 100oz bars, which at present are worth about $120,000. It could have been avoided with this relatively inexpensive ultrasonic gauge. I'd want to test the bar at a few different points, because sometimes the gold bars have tungsten slugs inserted in them and you might be measuring at a point where there is no tungsten, and be fooled into thinking the bar is real.
The greater the difference in the complex impedance, the more the reflection.
Thank You For Sharing,, this Demonstration,,,, very well done video,,,,
Using ultrasonic thickness gauges to test coins is tricky, as they need a flat surface to take a measurement (and most coins do not have a large enough flat surface, due to the images on the coin). However, it will work fine with silver, gold, or most other metals.
The bars were all reportedly purchased from individuals in China, and given how recently they were discovered, I feel pretty confident they were made in China. It certainly could have been made better easily (correct weight and shape, for one!).
Although you could pass the ultrasonic test, you would likely now have a substance that doesn't weigh the same as silver (possible off quite a bit), which would prevent you from getting a size/weight match.
Very informative. Thank you very much
What stops the wave from traveling through the bar and into the table the bar is laying on? I am curious as to how the wave stops at the end of the bar and bounces back? Or perhaps is there a lead on the opposite side of the bar that cannot be seen in the video?
This all-lead type is very new, we received our first report in late September, 2010. There should not be many of these on the market. It seems that they are all coming from small sellers in China, but at some point people in other countries will start selling the ones they bought (thinking they are real). At this point, all knowledgable dealers should easily detect these.
I also bought it in eBay. Around $150. Most of the sellers are from China, because the thickness gauge is produced there.
Thanks guys. Just check mine and they are A OK. Whew. I was sweating.
Will this device also work on Silver coins
& Gold bars / coins ?
Will device come with list of velocitys for different metals, or is this easily searchable etc ?
Thanks AG.....
@AboutAg Thank you :)
Will this work on silver coins, and gold bullion in general?
Can this be used to measure the thickness of a enclosed cylinder? My friend's family has a business of compressed air. They get metal gas cylinders from dealers and sometimes they send half the thickness than the requirement. Besides checking the weight there is no other weight. and many times they just add weight to the bottom of the cylinder. If the cylinder were to burst while being filled with compressed gas it could be bad for business and someone's life. They need some device like that.
Nice thanks
nice video. In your experience are fake silver bars common?
AboutAG, do you think ultrasonic thickness gauge will work on "Royal Canadian Mint" 10 oz silver bar? That 10 oz bar doesn't seems to have a flat surface at the back side of the bar.
+Consciousness Law Although I have not tried using an ultrasonic thickness gauge on a 10 oz RCM silver bar, from the looks of the bar, I think that unfortunately it would be very difficult (or impossible) to get a good reading.
@1231238502 We tried using a digital multimeter, but they aren't accurate enough to detect the difference in resistance between silver and other metals. It sounds like a nano-voltmeter might do the trick, but those are very costly.
Is Quality Silver Bullion (qsb) a reputable online dealer? Have you tested any of their bullion?
@sg142215 Yes, feel free to E-mail some pictures.
is the Ultrasonic Thickness Gauge as good as the XRF test?
Better, since it measure through the metal. XRF only do um thick surface analysis of metal composition. So yoy can't be certain what's inside your bar.
@@ptaeiy cool thx!