Re: Gum Sizing Brush, Roller, Tray
I use normal cook's gelatin, in UK you buy it in sachets containing about
12.5 grams. I make this up to 350 ml in water to make a 3.5% solution,
discard 150 ml, add 6 ml of 30% formalin to the remaining 200 ml. This
generously coats 20 sheets of paper about 30x23 cm. I discard remaining
solution and wash the brush immediately after coating, so I'm not sure how
well it would keep. At the rate I print, 20 sheets is a good number.
In the context of the discussion thread about brush versus immersion sizing,
I take Judy's point about immersion being a superior method in principle,
not least because you can print on both sides of the paper. However the
brush method for me is much less messy, much quicker, uses less gelatin and
less formalin, and clears very well for the three or four coats that I
normally use when gum printing. (In passing, I use gum made up from lumps. I
haven't had much success with lithographer's gum.) I haven't found paper
curling to be a problem (using Bockingford, and latterly Saunders Waterford
HP papers, 140lb/300gsm).
On 8/4/08 09:29, "C.Breukel@lumc.nl" <C.Breukel@lumc.nl> wrote:
> How long does the formalin/gelatin solution last, ie when does it
> start to harden?
> And what surface (roughly) can you coat with 200 ml ?
> Thanks & best,
>> -----Original Message-----
>> From: Henry Rattle [mailto:firstname.lastname@example.org]
>> Sent: maandag 7 april 2008 17:51
>> To: email@example.com
>> Subject: Re: Gum Sizing Brush, Roller, Tray
>> Like you I used to immerse paper in gelatin solution (often twice) and
>> in dilute formalin. Nasty fumes, as you say, though not too bad with
>> windows open. However the whole process was tedious and messy, with
>> gelatine and having to wait for paper to dry twice or even three
>> Then I tried brush sizing - ten times easier and just as effective. I
>> up gelatine at 3.5%, take 200 ml of that in a jam jar, stand that on
>> hot tray (hostess tray?) to keep it at about 130-140 deg F (55-60C)
>> 6 ml of 30% formalin. Then coat generously on one side of the paper,
>> flat (face up, of course...) on newspaper until cool, and finally hang
>> dry. I use a two inch decorators brush, and borrow the domestic
>> and plastic pegs for drying.
>> Compared to the immersion way, this is economical in gelatin, formalin
>> time, and seems to produce just as good results.
>> The fumes aren't bothersome (though I keep windows open and a fan
>> outwards) and I shut the room and keep out for the rest of the day,
>> be sure.
>> Best wishes
>> On 7/4/08 16:11, "Robert Newcomb" <firstname.lastname@example.org> wrote:
>>> When it comes to putting size on paper for Gum prints, have you
>>> brushing it on, using a small paint roller or dipping the whole
>>> in a tray of size to be the preferred method?
>>> When I first tied gum printing several years ago, I would immerse
>>> entire sheet in a tray of warm gelatin and then carefully drag the
>>> sheet over the edge of the tray to remove some of the excess, hang
>>> and dry. I believe this is the method in the "Gum Bichromate Book"
>>> which was my only guide at the time.
>>> I also vividly remember having to endure the burning eyes while
>>> large amounts of formalin - maybe thats why my hair is white?
>>> I saw Christina's post "I have not yet tried Kerik Kouklis' handy
>>> method of adding 6 drops of formalin per 10ml hot gelatin at time of
>>> brushing it onto paper which would probably be the ticket."
>>> So, have more experience people found brushing smaller amounts to be
>>> a better way?
>>> After some time away from printing, now that I have my darkroom back
>>> again, I'm ready to start again.
>>> thanks for the help!
>>> Robert Newcomb