paper gelatin / alum sizing, multitude of recipes

[Xandros]

Hi all,

I'm thinking about gelatin-based sizing again, and have researched different formulas online, and well it seems that there are as much different formulas / ratios / recipes as there are different printers.

Some people write to mix gelatin and alum hardener together before applying, some instruct to apply successive coatings of gelatin then alum several times, and each person gives different solution proportions. I could try all of them for sure, but that seems quite overkill. As all this is chemistry (albeit a bit complicated one), there should at least be a ideal gelatin/alum ratio optimal for hardening of the gelatin, which can then be more or less diluted in water and applied in different ways ... what do u think ?

 

[Loris Medici]

I only use (and recommend) formalin for hardening gelatin sizing... (0.2ml per 1g dry gelatin, I melt the gelatin and stir in the formalin, keep it hot, coat and discard the excess.) Can't you buy it in Belgium?

 

[Ian Grant]

There's two alums used in hardening gelatin, plain Alum a generic term usually means Potassium Aluminium Sulphate and it's used mainly in hardening fixers but only works in acid solution lower than about pH5.

The other, Chrome alum, is Potassium Chrome Sulphate which has greater hardening properties and is used in commercial film & paper emulsions as well as for Gelatin subbing layers.

Both Formaldehyde & Chrome alum work well when sizing with gelatin but the choice may depend on what the papers going to be used for.

Ian

 

[Xandros]

Ian, I can't get any chrome alum over here (unless I order it in big quantity online) and formalin (formaldehyde) is not openly available to the public I think, unless you're getting it online again. Where are u getting it in Istanbul ?

anyway, that doesnt change the question of the very different gelatin concentrations and techniques that everyone describes...

 

[Ian Grant]

My stocks of Chrome alum & Formaldehyde are back in the UK I've had them for years.

I've used both for subbing with gelatin and also in emulsions (I used to make them commercially). The actual quantity you need to add depends on the gelatin you're using, the degree of hardness required, and what you're trying to achieve that's why quantities are vague and vary a lot.

Ian

 

[Loris Medici]

Dry drugstores / pharmacies if you can't but it from a chemistry dealer (as I do it in Istanbul); maybe they'll give you a little (100ml?)... I understand there's a certain difficulty in obtaining it in Europe or the U.S. because it's a precursor chemical for narcotic drugs or some other controlled substances.

Edit: You may try to find an embalmer too; probably they stock formaldehyde...

 

[Hexavalent]

Formalin is sometimes available from fish aquarium suppliers. Glutaraldehyde is also sold as a medical sterilant, often used by tattoo artists. You may have to do a little research to find out what the brand names are in your locale.

As there is great variance in gelatin, there is also a great variance in the quantities/type of hardener required to achieve a specific result.
There is no real one-size-fits-all hardening formula.

 

[R Shaffer]

Hi all,

I'm thinking about gelatin-based sizing again, and have researched different formulas online, and well it seems that there are as much different formulas / ratios / recipes as there are different printers.

For sure there are a lot different formulas & techniques.

I am using 21g gelatin ( knox or photo grade ) in 1000ml H2O. I have used it hardened and unhardened. I use about 5ml of glyaxol or 2gr of Chrom Alum as a hardener. I just tried the chrom Alum for the 1st time a month ago and I think I like it a bit better than the glyaxol. I combine the hardener with the gelatine and soak the sheets in a tray for 10min. A very light squeegee and hang to dry. I find letting them cure for at least a few days hardens better. I use this for gum printing and for gum-overs.

 

[Xandros]

Ok thanks all, I tried pharmacies for glyoxal here and its extremely expensive (like 20 € for 10ml), have to ask for formalin & glutaraldehyde yet ... don't have access to chrome alum and potassium alum works but it swells after a few layers so maybe I need to re-size between print layers

 

[Ian Grant]

Are you still using Avoirdupois weights ? 2gr is 2 grains or do you mean grams ?

Ian

 

[R Shaffer]

Are you still using Avoirdupois weights ? 2gr is 2 grains or do you mean grams ?

Ian

Grams not grains. Didn't know gr is grains.

 

[Ian Grant]

Grams not grains. Didn't know gr is grains.

Thanks, while I guessed you probably meant Grams many US books use Avoirdupois weights as well, and surprisingly one recently (in the last 10 years) uses no metric at all, and the convention is to use Gr for Grains.

The other reason for querying is 4 grams of Chrome alum to 21 grams of Gelatin seems rather high, but then you seem to be saying you soak in water for 10 minutes afterwards, so that would remove the excess anyway.

My own use of Chrome alum was as a 10% solution and less than 5ml of that for substantially more Gelatin in a subbing layer. The rate in commercial B&W emulsions can be in the region of 4-5ml of the 10% Chrome alum per 3 kilograms of Gelatin, but then they aren't wanting the same degree of hardening.

Ian

 

[Xandros]

ok finally I managed to find some 30% formaldehyde solution over here, quite cheap surprisingly (5€ for 1L). I read some people put "drops" into the gelatin solution, but well it's quite hard to quantify ... is there some proportion / recipe even if just for a start ?

 

[Loris Medici]

Xandros, I've given the proportion I use few messages ago: 0.2ml per 1g gelatin. I soak the gelatin in cold water, wait 15 minutes (15 minutes is perfectly fine for 3%, you may need more time for stronger dilutions...), heat the solution to 40C using a coffee mug warmer (my 500ml beakers fit perfectly on the heating pad), mix the formalin into it, stir and size the papers with a brush. I then discard the excess. 100ml of solution is plenty for any reasonable sized batch...

Now I don't say that's the absolute correct proportion, all I say that's what works for me w/o any problems...

Regards,
Loris.

P.S. Dry the papers in a well ventilated room!

 

[Xandros]

Thanks Loris ! Yep I decided to try formalin because I'm printing in a room with a big window so it should do the trick without endangering anyone

 

[R Shaffer]

The other reason for querying is 4 grams of Chrome alum to 21 grams of Gelatin seems rather high, but then you seem to be saying you soak in water for 10 minutes afterwards, so that would remove the excess anyway.

Ian

I used 2g Chrom Alum to 21g Gelatine. Not sure where or how I came up with that quantity. But it does make the gelatin a lovely aqua-marine color and I was able to put 4 layers of gum over a cyanotype without any staining. No water bath after though. I just shuffled the sheets in the tray for 10 minutes in the warm gelatin.

One thing I did notice is that I did get a little darkening of the cyanotype around the edge of the coated area during drying. It vanished during development and the print looked good ( no fogging ), but I was a bit concerned I had some sort of reaction going on.

 

[Brownman]

ok finally I managed to find some 30% formaldehyde solution over here, quite cheap surprisingly (5€ for 1L).

Congratulations for finding that formerly very elusive chemical (well, post 9/11?)! I was just about to report here my thrill for finally being able to get a liter of 30% FORMOL from a high profile Paris photographic supplier like Prophot ( i can see it on their website also so i suppose they can deliver by post but im not sure).
Things seems to be easing up for us alt printers here recently because im seeing more local sellers of chemicals to end users now than when i arrived here (Paris) 5 years ago. I have not had problems with unsized Fabriano Artistico with up to 4 or 5 layers of gum and gumovers but there's that part of me thats not happy knowing im limiting myself to possibilities.
thank you also Loris for posting your mix and procedure, now i can try sizing!!!!

 

[Ian Grant]

I used 2g Chrom Alum to 21g Gelatine. Not sure where or how I came up with that quantity. But it does make the gelatin a lovely aqua-marine color and I was able to put 4 layers of gum over a cyanotype without any staining. No water bath after though. I just shuffled the sheets in the tray for 10 minutes in the warm gelatin.

One thing I did notice is that I did get a little darkening of the cyanotype around the edge of the coated area during drying. It vanished during development and the print looked good ( no fogging ), but I was a bit concerned I had some sort of reaction going on.

I think if it was me I'd do some tests, making up a 10% solution, starting around the ratio as Loris suggest for formaldehyde, maybe a little less.

Ian

 

[Xandros]

Brownman, I was very surprised to see how easy it was (drugstore) and it's a usual plastic bottle like those they use to sell bleach or such basic chemicals at the supermarket ...

 

[Brownman]

Xandros, i just saw you are in Brussels. My first batch of important chems came from Roger Kockaerts of atelier PH7 Dead Link Removed He doesn't have formaldehyde listed but i wont be surprised if he have stashed somewhere if you ask him. I would love to pay him a visit again and get more plus get inspired with his impressive collection of alt work personal and from other artists all over the world. Great man.

 

[Loris Medici]

BTW, as a last note: I use foam brushes for sizing, not good synthetic bristle ones... The brush absorbs a good amnt. of sizing and if that doesn't suffice while coating, you dip it in the solution once more. Keep the brush in the warm solution (while working) and wash it well as soon as the job's done. If not, it will be useless for the next time. (Due to the hardened gelatin left inside.) Clean the vessel by first rinsing it with water and then filling it up to the top using 1+5 diluted household chlorine bleach. A couple of hours is enough, you'll be surprised how much gelatin stays in the container - even after a good wash. (It will show up as clumps clouding the solution, after some time...)

 

[Xandros]

Brownman, I know this place via the Internet but never went there yet, we have however a very old drugstore in the center where they have a lot of chemicals, potassium dichromate, pigments, formol, metabisulfite, alum and whatnot. ppl come from all across belgium to go get their stuff there : http://www.le-lion.be/

Loris, yep thats what I am doing already. I'm surprised though that such a small amount of formalin is able to harden all that gelatin. I just applied a single coating of size using this technique, same paper and same proportions but three different gelatins (first test).

 

[holmburgers]

What kind of alum is this? Is it pure enough to use for all the aforementioned purposes?

http://www.amazon.com/Dragon-88-Brand-Alum-Crystals/dp/B002B5QWBI

I saw this at a Chinese Market in my town and was quite surprised, but I guess I didn't have a good idea of what alum really was.

 

[Hexavalent]

What kind of alum is this? Is it pure enough to use for all the aforementioned purposes?

http://www.amazon.com/Dragon-88-Brand-Alum-Crystals/dp/B002B5QWBI

I saw this at a Chinese Market in my town and was quite surprised, but I guess I didn't have a good idea of what alum really was.

If it's for food use, it's most likely potassium aluminum sulphate - not 'chrome' alum.
K Alum will harden gelatin, but not to the extent that chrome does. Both perform better with the addition of some acid.

 

[Jerevan]

If it's for food use, it's most likely potassium aluminum sulphate - not 'chrome' alum.
K Alum will harden gelatin, but not to the extent that chrome does. Both perform better with the addition of some acid.

Well, there goes that money down the drain - I bought the wrong kind, Pot Alum. Does the bloom of the gelatin make any difference to the hardening properties?