Ep. 97 Bill Crowe at The Spellman Museum: Live Expertizing Event Sponsored by NobleSpirit (Part 2)
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- čas přidán 25. 12. 2022
- On December 3rd, 2022, US expert William T Crowe reviewed material at the Spellman Museum brought in by members and other guests to offer "on the battle field" opinions regarding authenticity and condition.
In a first of many event, sponsored by NobleSpirit, these events look to bring collectors more in touch with the way they examine stamps and inform collectors on how to make better buying decisions.
For more information on the Spellman Museum and events like this one please visit: spellmanmuseum.org/
Please bring back Conversations with Philatelists, we miss you!
This may be the best (2) episodes you have produced. I'd love to see more conversations just like this with expertizers.
Спасибо за обзор ! Марки это история ! Это то что должно нас объединять !
Most informative and interesting. Thank you for presenting this to us.
We miss conversations with Philatelists!
where are you two
Is this channel still up and running?
Very interesting video. Thanks
What a shame you gave up. Your channel was the best. Sad.
CwP is creeping up on Ep. 100~!~ Would like to be the first to say congratulations! And is there any leaks on if you are planning anything special?
Did you all get lost?
For the most part philatelists, including this gentleman, have their chemistry completely wrong. We tend to think of aging as an "oxidation" process because if you leave iron out it will rust (oxidize). Poorly kept stamps develop "rust" spots so it must be oxidation, right? Not quite. These are created by microorganisms feeding on the sugars of the gum when the environment conditions (temperature and moisture) are right. So, microbial process, but NOT oxidation.
Now about inks, which in the XIX century were mostly mineral based. Red pigments may have come from red ochre (a mixture of iron oxides), or vermillion (mercury sulfide) among others. When stored in poorly aerobic, moist conditions, such as inside a box in a basement, these metals will either disproportionate to get to their most stable form or react with its environment, most likely oxidizing the paper they are in contact with. For example, mercury sulfide (HgS) which is red, will go to Hg2S which is black, giving the ink a darker tone. When we think about the metal, this is a REDUCTION process.
Now the gentleman is correct in saying we restore the original ink colors (the process he calls de-oxidation) with hydrogen peroxide. This chemical is however an oxidant, so his claim to de-oxidize using an oxidant makes no sense. Same for all the stuff about removing sulfur and an extra oxygen radical someplace
In summary, ink aging is better explained by a REDUCTION process which results in darkening of the color. The process can be reversed by OXIDATION of the inks with chemical oxidants such as hydrogen peroxide.
Modern inks are a completely different beast as the pigments are made from organic compounds instead of minerals. They tend to deteriorate to lighter shades and their major enemy is sunlight which promotes the generation of radicals. Not the topic of this video so I'll stop here.
Last video was 5 months ago. Are you guys ok what s going on?