Loading…

Blending Gelatin sensitizer Solutions-completing Gelatin Plate

Posted by takumi suzuki on 14.2016 English   0 comments   0 trackback
It’s not exaggeration to say that the gelatin plate is the life of collotype. How prints appear changes depending on how to blend gelatin sensitizer. There used to be a lot of collotype printing companies, and the same numbers of recipes existed.

Following is the current blending recipe of Benrido Collotype Atelier.

Gelatin1         720g
Gelatin2         720g
Water             15000ml
Ammonium Dichromate   180g
Potassium Dichromate    180g
Lead nitrate           30g
Benzoin tincture        180ml
ethanol         180ml


Blending of gelatin sensitizer 1 : chemicals
Above chemicals are broadly separated into three categories.
A) Gelatin
B)Sensitizing materials: Ammonium Dichromate, Potassium Dichromate
C)Assistants: Lead nitrate, benzoin tincture, ethanol
ゼラチン


Two kinds of gelatin :720g each



Main ingredient of sensitizer is gelatin. Gelatin for collotype once existed but has been discontinued as decline of collotype. And then we used photographic gelatin. But today, it’s not easy to purchase photographic gelatin anymore because of digitalization.
So now, we uses gelatin for food of Nitta Gelatin inc.

We did various tests when we were changing photographic gelatin to edible one. We judged gelatin’s aptitude for collotype by stiffness/softness, viscosity, strength of gel, tones, and printing-resistance. As a result of tests, now we decided to blend the same amount of two kinds of gelatin: 1)high-viscosity, soft gelatin 2)Low-viscosity, tough gelatin.
重クロム酸アンモニウム





Ammonium Dichromate (NH4)2Cr2O7
重クロム酸1
180g

 Potassium Dichromate K2Cr2O7
重クロム酸カリウム
重クロム酸2
180g

Potassium Dichromate, itself is resistant to light. However, it responds to light quickly when it combined with organic matter. Two kinds of Potassium Dichromate are necessary for collotype.
Each of them has different characteristics. Ammonium Dichromate is more photosensitive than Potassium Dichromate. On the other hand, Potassium Dichromate has better preservability because it has milder photosensitivity compared to Ammonium Dichromate. When collotype was invented, only Potassium Dichromate was used. Later, recipe of blend same amount of two kinds became popular. Benrido follows it. However, the record in 1981 shows there was a company which mixed two kinds of Dichromate 10:69 but not 50:50.


硝酸鉛

Lead(Ⅱ)Nitrate Pb(NO3)2
硝酸鉛1
30g

When mixing Nitrate with dichromate, it forms yellow lead chromate. Unclear Yellow color helps to see picture when exposure and ink when prints. It is said that using Nitrate was started in Japan. In Europe, Nitrate is not used. So, plates are clear.

安息香チンキ




Benzoin Tincture 180ml

Use of Benzoin Tincture was also devised in Japan. When gelatin sensitizer is put and dried, small spots appear on the surface of sensitizer. If spots are left, spots will appear in images.
Benzoin Tincture prevents spots from appearing. We mix it with ethyl alcohol in gelatin solution.





Blending of gelatin sensitizer 2: mixing chemicals
ゼラチン感光液1




Gelatin (center) two kinds of dichromate (left) Nitrate(right)




Bathe two kinds of gelatin, 720g each in 12L of purified water, and let it swell. Dissolve the gelatin by putting the bowl in hot water for one hour.
Add 1L purified water each to two kinds of dichromate and nitrate. And dissolve them by putting the bowl in hot water as gelatin.
If you bathe gelatin in water too long, gelatin starts to melt, intensity of jelly decreases, and becomes no longer useful.


ゼラチン感光液2
Add Ammonium Dichromate into gelatin solution.

ゼラチン感光液3
And then, add Potassium Dichromate K2Cr2O7

ゼラチン感光液4
Alcohol (upper), Benzoin Tincture (lower)

ゼラチン感光液5
At last, add Nitrate.

ゼラチン感光液6
Adding nitrate changes solution into bright yellow.
ゼラチン感光液7

The first filtering with a funnel and a cloth

ゼラチン感光液8
This recipe makes gelatin sensitizer solution for a couple of days.

ゼラチン感光液9

Let it cool off and leave it for one night to make it mature. More than 10 hours is necessary for maturing process. By maturing, plates gain strong printing resistance.



Shitahiki treatment

Let the gelatin sensitizer sleep for one night, and at the next day, making of gelatin plate is done. Shitabiki is done as a pretreatment of gelatin plate making. It works as middle layer to connect glass surface and gelatin sensitizer surface. Without this pretreatment surface of gelatin layer falls off.
Main material is water glass. As an additive, we use beer. Some uses gelatin or the white of eggs but beer is the most stable.
Brand of beer doesn’t matter. But no low malt beer (we tested).

下引き4

Sodium Silicate Na2Si4O9





下引き2





Solution of beer and water glass. 3ml of Water Glass+ water 30ml and beer 30ml

下引き1

Applying Shitabiki solution
下引き3
Place shitabiki finished glass plates in dryer machine horizontally.


There is another way of shitabiki, but Benrido does a cloth wiping style “Shitabiki”. After Shitabiki treatment, put plates inside a dryer adjusting to make it horizontal.














completing Gelatin Plate

ゼラチン感光液10
Leave gelatin for one night. Melt it again.

サポニン

Saponin 13g+Water180ml(For three days)


Dissolve gelatin in hot water, again.
Filter it (Second time). Adding Saponin to it just before putting it on the glass plate. Saponin activates surfaces. It prevents gelatin from lathering.



Put Gelatin sensitizer solution on pre-treatment (Shitabiki) finished glass plate.



Make it even.

刷版1

Delete bubble by picking if there is any.
刷版2

Require two people to treat the biggest sized glass plate.
刷版3

刷版4
Place the glass plates in dryer machine horizontally.

乾燥機


Dry for 1hour and half at 55℃.



When it becomes normal temperature, drying process is done.
Put them in dark for exposure process on the next day.
関連記事


  • password
  • 管理者にだけ表示を許可する

trackbackURL:http://takumisuzuki123.blog.fc2.com/tb.php/93-045b8b7c

プロフィール

takumi suzuki

Author:takumi suzuki
【コロタイプの過去・現在・未来。創業明治20年の京都 便利堂が100年以上にわたって続けているコロタイプ工房より最新の情報をお届けします】
Japanese:www.benrido.co.jp
English:www.benrido-collotype.today

カテゴリ

  • 【コロタイプとは? what is a collotype?】(1)
  • 【コロタイプ、やりませんか collotype academy】(15)
  • 【コロタイプで作品集をつくりませんか?】(1)
  • 【今日のコロタイプ】 (25)
  • 【コロタイプ技法解説 collotype process】(4)
  • 【コロタイプの歴史】(2)
  • 【古典印画技法 Altanative Process】(3)
  • 【コロタイプギャラリー】(25)
  • 【書棚のコロタイプ】(3)
  • 【コロタイプ技術の保存と印刷文化を考える会】(2)
  • 【法隆寺金堂壁画ガラス乾板保存プロジェクト】(3)
  • 【文化財を護る技―「認定保存技術」プロジェクト】(0)
  • 【メディア取材】(5)
  • 未分類(1)
  • English(8)
  • HARIBAN AWARD(7)

全記事一覧

takumisuzuki123