The Uranotype Thread

[dpn]

Wonderful shots Thomas!

[tgtaylor]

Thanks Dan.

Thomas

[tgtaylor]

Untitled - San Francisco 2016



This is the 4th and final rehash of this print. When I printed the 3d yesterday I had intended on coating the paper close to the tick marks placed along the edges of the 5x7 negative on the 8x10 paper but screwed-up when, out of habit, I started coating from the top of the sheet. When coating from near the negative's tick marks, the image along with its resulting border allows me to mount it on the same size board as my 8x10 prints without it appearing out of place. Although 5x7 is smaller than 8x10, the surrounding border makes it appear larger than it is and I can keep the same size board and frame, 16x13, which to me is both appealing economical when using 32x40 board as there is almost no waste.

For this 4th reprinting I decided to keep everything identical with the 3d printing but add just 2 more drops of potassium dichromate to the sensitizer both increase the dmax and slightly reduce the red coloration of the stature. It worked and I got a brighter and more lively red!

I wonder what the longevity of the Uranotype is?

Thomas

[Fr. Mark]

Longevity...what's the main isotope's half life? Multiply that by 10 and that will set an upper limit!

[tgtaylor]

LOL... Yes the half life is on the geological time scale - in the millions of years - but does the print "fade" during the human lifetime due to UV exposure, etc?

Thomas

[Mark Sawyer]

I have quite a few I made in the late 1970's that still look very nice.

[roy7]

Nice work

[koraks]

Longevity...what's the main isotope's half life? Multiply that by 10 and that will set an upper limit!

It's 238 which is stable (not radioactive) and therefore doesn't have a half life. In that sense, the lifetime is infinite This is only physical stability and says nothing about chemical decay of course.

[tgtaylor]

Thanks Roy7.

On the half-life of U-238:

Around 99.284% of natural uranium is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years, or 4.468 billion years).[1] Depleted uranium has an even higher concentration of the 238U isotope, and even low-enriched uranium (LEU), while having a higher proportion of the uranium-235 isotope (in comparison to depleted uranium), is still mostly 238U. Reprocessed uranium is also mainly 238U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as uranium-234, uranium-233, and uranium-232.[2] https://en.wikipedia.org/wiki/Uranium-238

Atomic nuclei consist of protons and neutrons, which attract each other through the nuclear force, while protons repel each other via the electric force due to their positive charge. These two forces compete, leading to some combinations of neutrons and protons being more stable than others. Neutrons stabilize the nucleus, because they attract protons, which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus; if too many or too few neutrons are present with regard to the optimum ratio, the nucleus becomes unstable and subject to certain types of nuclear decay. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, or electron capture. Many other rare types of decay, such as spontaneous fission or cluster decay are known. (See radioactive decay for details.) https://en.wikipedia.org/wiki/List_o...ty_of_isotopes

Thomas

[Fr. Mark]

Thomas you beat me to it'