Gelatin preservative
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Marek Matusz
All,
Does anybody have any experience with using preservatives for gelatin solutions? I know its cheap and people usually make it foe one time use, but I want to mix stock solutions and keep them stable for a few weeks
Thanks Marek
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Jorj Bauer
Thymol works well for me. My notes say ... 1mL of a 30% w/v thymol solution (in ethanol, not water), per liter of gelatin.
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-- j
On 12/10/21 3:56 PM, Marek Matusz wrote:
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Richard Sullivan
Freeze them. Make ice cubes of a known size and melt them in the microwave. Worked great for carbon tissue. I could grab and melt 4 black and one yellow for a pleasant brown. --Dick Sullivan
On Fri, Dec 10, 2021 at 2:36 PM Jorj Bauer <jorj@...> wrote: Thymol works well for me. My notes say ... 1mL of a 30% w/v thymol
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Keith Fleming
Dick Sullivan, Your comment on mixing black and yellow brought back other memories of my youth. Wasn’t the recipe for the color of “Marine Corps Green” paint 3 parts black and 1 part yellow? Korean War vets used to tell us young guys that knowing the right mixture was important knowledge during the Korean War if you stole an Army jeep or truck for your Marine unit. A quick coat of Marine Corps green paint and a vehicle number in yellow was enough to hide the acquisition. I have it on good authority that in 1966 the MP’s at Martine Corps Air Station, Iwakuni finally officially learned that one of their jeeps had been written off as “lost in combat” by the Army back in 1953. Keithj Fleming
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From: Richard Sullivan
Sent: Friday, December 10, 2021 2:01 PM To: altphotolist@groups.io Group Moderators Subject: Re: [altphotolist] Gelatin preservative
Freeze them. Make ice cubes of a known size and melt them in the microwave. Worked great for carbon tissue. I could grab and melt 4 black and one yellow for a pleasant brown.
--Dick Sullivan
On Fri, Dec 10, 2021 at 2:36 PM Jorj Bauer <jorj@...> wrote:
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Ryuji Suzuki
2-phenylphenol (sodium salt) works well, at a ratio of about 1/100 to 1/20 of the gelatin weight. (I used to use 1/50 or so and then refrigerated the mix, which lasted for a long time.) Ryuji Suzuki "When people are free to do as they please, they usually imitate each other. Originality is deliberate and forced, and partakes of the nature of a protest." (Eric Hoffer)
On 10 Dec 2021, at 15:56, Marek Matusz wrote:
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Francis Dubois
I use a little bit of formalin
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BOB KISS
Please advise: I recall threads re Gluteraldehyde. Is it for hardening gelatin or for preserving it...or for both!
From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of Francis Dubois
Sent: Saturday, December 11, 2021 8:19 AM To: altphotolist@groups.io Subject: Re: [altphotolist] Gelatin preservative
I use a little bit of formalin
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Clay Harmon
I find gluteraldehyde primarily useful for yellowing paper.
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;^) Clay
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John Brewer
Formalin hardens gelatine, I use it for hardening gelatine size for gum.
--
John Brewer www.thevictorianphotographer.com www.johnbrewerphotography.com workshops:equipment sales:chemistry sales Silver nitrate sales
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Christina Z. Anderson
Bob,
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I was really surprised when Francis said they used formalin to preserve gelatin. Glut and formalin both harden gelatin, but maybe it’s the amount Francis uses that is so small it doesn’t harden it. The amount I use of glut to harden is 6 ml of 2.5% per liter of gelatin and that is really small. The amount of formalin to harden is 20 ml of 37% formalin. So you use more, and stronger, to harden. Maybe 1 ml isn’t a big deal. Neither one hardens gum arabic to my knowledge but both harden gelatin. Here are my notes for preservative for GUM (not specifically gelatin): •1/2 - 1 1/2 ml of 100% thymol (10g mixed in 10ml isopropyl alcohol) • 3ml phenol (carbolic acid) • 3ml formalin (formalin does not harden gum as it does gelatin) • 8g sodium benzoate powder, dissolved in a bit of warm water first. • 5g Bayer Preventol ON Extra Flakes at Kremer Pigments, order # 78740) However, I will say from experience that whatever they used to use to preserve gum, formalin or mercury, back in the day, was much better than thymol or sodium benzoate which I use now. When Daniel Smith quit their retail sales of gum arabic I bought 8 gallons from them. I loved their gum and I have about a gallon left and it is still perfectly well preserved and has not darkened in color over a decade. Plus, I hate to tell you, it was $80 a gallon back then and now it’s tripled. This summer the gum arabic we ordered for a workshop, preserved with sodium benzoate, came sour and stinky. Maybe I’m the only one with a sensitive nose but it makes me gag. Worked OK but it gets acidic and leads to non-image formation/staining. Back in the 1800s they thought adding lemon juice to gum was a good thing because it would help exposure and hardening, which it does—all over. I would add drops of ammonia to make this gum neutral if it were in my dimroom. But again we’re talking gum here and I imagine the carbon printers have a slew of advice better than this for gelatin. Chris
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Christina Z. Anderson
I find glyoxal does too but years ago we had this discussion on the list that it was the amount. If too much of glut or glyoxal is used it definitely yellows. I have not had one bit of yellowing with 6 ml 2.5% but noticed immediate yellowing when a student accidentally used 6 ml of 25% :)
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Chris
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Don Nelson
Thymol works
So does Sodium benzoate
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Nicole Hagesteijn,
I have tried thymol; for me it did not work. I was advised clove oil (kruidnagelolie) by a professional paint maker (Verfmolen De Kat in the Netherlands). For some years now I have used this, only three drops on top of the gum and on top of the self made aquarel paint. It works perfect.
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I have no idea though how this would work with gelatine. Vriendelijke groeten, Nicole Hagesteijn-Pezie
Op 11 dec. 2021 om 17:22 heeft Don Nelson <ac7zg@frontier.com> het volgende geschreven:
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Frank Gorga
A bit of chemistry... Formaldehyde and gluteraldhyde, as their names suggest, are both aldehydes. The aldehyde function in these compounds is the "active" part of the molecules, both for their activity as preservatives and as hardeners. One difference between these molecules is that formaldehyde has a single aldehyde group and gluteraldhyde has two. This means that gluteraldhyde is a much more effective cross linker (hardener) than is formaldehyde. In practice, the concentration is critical... gluteraldhyde will cause hardening at lower concentrations than formaldehyde. How much lower and how the concentration leading to hardening relates to their effective concentrations as a preservative is probably best determined by experience. As I have no experience in this regard, I'm not about to make a specific recommendation regarding concentrations. My gut feeling is that a compound such as thymol is probably a better choice as a preservative than either of the aldehydes as there is no possibility of cross linking gelatin.
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Jim Patterson,
You can also use Potassium Sorbate in a similar manner to Sodium Benzoate. It is available at brew supply stores or on line.
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On Dec 11, 2021, at 11:13 AM, Nicole Hagesteijn, <n.hagesteijn@gmail.com> wrote:
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Richard Sullivan
Green, maybe. I may have added red as well. It's been a while. I've read in early works to never freeze gelatin, not so. A microwave makes quick work of melting the gel. I was stationed at Marine Air Station Futenma, 1960-1961. I graduated as a Corporal. --Dick
On Fri, Dec 10, 2021 at 4:21 PM Keith Fleming <kfleming@...> wrote:
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Marek Matusz
Thanks to all tat replied. I will try thymol and sodium benzoate. Both chemicals on the shelf. I actually like thymol smell.
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Freezing sounds like a good idea. I actually put a leftover mix in the freezer to test Best Marek
On Dec 11, 2021, at 11:34 AM, Jim Patterson, <jimbobnola@cox.net> wrote:
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BOB KISS
Similar to what others have recommended, I make a tincture (alcohol solution) of 5% thymol and use it for a number of purposes...add to cyanotype soln to prevent mold, treat silver gelatin prints to prevent mold on them in our very damp Caribbean atmosphere, and I am in the habit of wiping a cotton ball wetted with the tincture on the back of my hand made prints to discourage mold and mildew growth.
-----Original Message-----
Thanks to all tat replied. I will try thymol and sodium benzoate. Both chemicals on the shelf. I actually like thymol smell. Freezing sounds like a good idea. I actually put a leftover mix in the freezer to test
Best Marek > On Dec 11, 2021, at 11:34 AM, Jim Patterson, <jimbobnola@...> wrote: > > You can also use Potassium Sorbate in a similar manner to Sodium Benzoate. It is available at brew supply stores or on line. >> On Dec 11, 2021, at 11:13 AM, Nicole Hagesteijn, <n.hagesteijn@...> wrote: >> >> I have tried thymol; for me it did not work. I was advised clove oil (kruidnagelolie) by a professional paint maker (Verfmolen De Kat in the Netherlands). For some years now I have used this, only three drops on top of the gum and on top of the self made aquarel paint. It works perfect. >> I have no idea though how this would work with gelatine. >> >> Vriendelijke groeten, >> Nicole Hagesteijn-Pezie >> >>>> Op 11 dec. 2021 om 17:22 heeft Don Nelson <ac7zg@...> het volgende geschreven: >>> >>> Thymol works >>> So does Sodium benzoate >>> >>> >>> >>> >>> >> >> >> >> >> > > > > > >
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Don Bryant
Ditto what Chris wrote. We did testing of glyoxal and several papers and all tests yellowed. Could be test be considered scientific or definitive? Probably not, but rigorous enough to conclude glyoxol can yellow at widely agreed upon concentrations. Well my 2 cents - time to raise my mask again, Don Bryant
On Sat, Dec 11, 2021 at 11:15 AM Christina Z. Anderson <christinazanderson@...> wrote:
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