In case you haven't heard...
- Lilah
- Posts: 1444
- Joined: Mon Nov 10, 2014 4:09 pm
- Real Name: Lilah Blinkman
In case you haven't heard...
I have a lot of family in the USPS and am patiently waiting for these to "debut"!!
http://earthsky.org/astronomy-essential ... 3131c612c3
http://earthsky.org/astronomy-essential ... 3131c612c3
Make it so,
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
- Deane Clark
- Posts: 2459
- Joined: Wed May 19, 2004 11:38 pm
- Location: Mpls
Re: In case you haven't heard...
Cool! I didn't know "eclipse stamps" were a thing. I may have to pick up a sheet for next year's stamp supply.
Deane Clark
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
- Lilah
- Posts: 1444
- Joined: Mon Nov 10, 2014 4:09 pm
- Real Name: Lilah Blinkman
Re: In case you haven't heard...
I know, these look awesome. My sister said they are really cool! I will likely buy extra so I can use some and save some.
Make it so,
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
- TrenaJ
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- Real Name: Trena
- Location: Vadnais Heights
- Contact:
Re: In case you haven't heard...
Very very cool. I will have to get some as well...never to be used.
Trena Johnson
MAS President 2023-2024
CGO Chairperson
JJC/CGO/ELO/LLCC Keyholder
AstroSky 14in f/4.9 Truss Dob
Orion StarSeeker IV 150mm GoTo Reflector
MAS President 2023-2024
CGO Chairperson
JJC/CGO/ELO/LLCC Keyholder
AstroSky 14in f/4.9 Truss Dob
Orion StarSeeker IV 150mm GoTo Reflector
-
- Posts: 608
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- Real Name: Mark Job
Re: In case you haven't heard...
I have a few sheets on order at the local PO. I have friend on staff.
Mark
Mark
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- Location: Bloomington, MN
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- Posts: 608
- Joined: Thu Oct 28, 2010 3:52 pm
- Real Name: Mark Job
Re: In case you haven't heard...
Got mine!
They are very cool.
They are very cool.
- Deane Clark
- Posts: 2459
- Joined: Wed May 19, 2004 11:38 pm
- Location: Mpls
Re: In case you haven't heard...
I know.... “Why is he resurrecting that thread from 2017?”
Anyway, I have recently received a couple pieces of mail with the eclipse stamp on them, and I’ve found that warming the stamp with your finger or by breathing on it no longer makes the moon show up. Has anyone else noticed this? I’m kind of glad I never bothered to buy a bunch of them now that I know this.
Anyway, I have recently received a couple pieces of mail with the eclipse stamp on them, and I’ve found that warming the stamp with your finger or by breathing on it no longer makes the moon show up. Has anyone else noticed this? I’m kind of glad I never bothered to buy a bunch of them now that I know this.
Deane Clark
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
- Lilah
- Posts: 1444
- Joined: Mon Nov 10, 2014 4:09 pm
- Real Name: Lilah Blinkman
Re: In case you haven't heard...
Just checked mine and they don't work. I just have one sheet that I received as a gift.
Make it so,
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
- Deane Clark
- Posts: 2459
- Joined: Wed May 19, 2004 11:38 pm
- Location: Mpls
Re: In case you haven't heard...
Well, at least they still work as stamps!
Deane Clark
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
Eagle Lake Observatory keyholder
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
- Dale Smith
- Posts: 433
- Joined: Sat Dec 23, 2006 1:11 pm
- Location: Plymouth, MN
Re: In case you haven't heard...
There is a Wikipedia article on this stamp.
https://en.wikipedia.org/wiki/2017_Tota ... ipse_stamp
It mentions that the USPS has said UV (ultraviolet) light can cause the thermochromic ink to degrade so the stamps should be shielded from sunlight.
I find this topic interesting because I am an ink chemist. While I have never personally formulated inks containing thermochromic dyes, I do not find this sensitivity to sunlight surprising. One of the common classes of thermochromic materials are leuco dyes. These are dyes that switch between colored and colorless forms. Many of the common ones are based on triphenyl methane dyes, which are cheap and very widely used in the printing industry. They have notoriously poor fade resistance to light and heat.
https://en.wikipedia.org/wiki/2017_Tota ... ipse_stamp
It mentions that the USPS has said UV (ultraviolet) light can cause the thermochromic ink to degrade so the stamps should be shielded from sunlight.
I find this topic interesting because I am an ink chemist. While I have never personally formulated inks containing thermochromic dyes, I do not find this sensitivity to sunlight surprising. One of the common classes of thermochromic materials are leuco dyes. These are dyes that switch between colored and colorless forms. Many of the common ones are based on triphenyl methane dyes, which are cheap and very widely used in the printing industry. They have notoriously poor fade resistance to light and heat.
- Lilah
- Posts: 1444
- Joined: Mon Nov 10, 2014 4:09 pm
- Real Name: Lilah Blinkman
Re: In case you haven't heard...
Hmm, well mine were in the original envelope and in a dark drawer. So, they were definitely shielded from sunlight!
Make it so,
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
Lilah Blinkman
MAS Outreach Coordinator
ELO Program Coordinator
- Dale Smith
- Posts: 433
- Joined: Sat Dec 23, 2006 1:11 pm
- Location: Plymouth, MN
Re: In case you haven't heard...
Note that I said light and heat. Heat could encompass both rapid changes due to elevated temperature or slow changes at room temperature, such as in a dark drawer.
Another possibility are pH changes. Many triphenyl methane dyes can be used as pH indicators (materials that change color with changes in acidity). As it ages paper tends to create acidic decomposition products.
However, I must add that without knowing the specific thermochromic dye used all I can do is speculate.
Another possibility are pH changes. Many triphenyl methane dyes can be used as pH indicators (materials that change color with changes in acidity). As it ages paper tends to create acidic decomposition products.
However, I must add that without knowing the specific thermochromic dye used all I can do is speculate.