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定影液作用原理: 先有個化學的概念

主成分"硫代硫酸根"

2 S2O32− + AgBr → [Ag(S2O3)2]3− + Br−

主成分"硫酸鈉"

The sulfite is often described as an oxygen scavenger. It has a powerful tendency to react with oxygen; this prevents the oxygen from reacting with the thiosulfate, which would shorten the life of the fixer. @ http://www.heylloyd.com/technicl/plain.htm

 

定影液種類:

硫代硫酸根是定影液的主成分, 主要有下列種類:

Sodium thiosulfate (  Na2S2O3, 硫代硫酸鈉, 俗名:海波(hyoo) ) based Fixer 

傳統定影液

F5 Fixer (有強烈的味道)

F6 Fixer 無味的堅膜定影液



F6 Fixer  

water @125 degrees F

 750mL

sodium thiosulfate pentahydrate, 

( 或 sodium thiosulfate anhydrous,
in water at about 80 degrees F, 160 grams )

 240 grams        
sodium sulfite anhydrous 48mL
Kodak 'Kodalk' Balanced Alkali (sodium metaborate) OR Borax (sodium tetraborate decahydrate) 15gm
potassium alum (hardener) 15gm
water to make 1L

Ammonium thiosulfate ( (NH4)2S2O3, 硫代硫酸銨 ) based fixer

Kodak® Rapid Fixer
ILFORD® Rapid Fixer

 

 

 

 

堅膜劑 (Hardener)

 

 

 

 

預期的定影時間:

  • 2x Film clearing time

"Take a piece of scrap unprocessed film and place a drop of the working strength fixer on to a small part of the emulsion side. Leave it until the emulsion under the drop is a clear spot, this should take around 30 to 60 seconds. Immerse the piece of film in the fixer bath and using a stop clock time how long it takes for the rest of the film to clear. Clearing can be judged by comparing the surrounding film area with the clear central spot. The time taken for the rest of the film to clear is the clearing time. The fixing time needed is double the clearing time."

Ref: FACT SHEET, RAPID FIXER, ILFORD @ http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

 

定影液的藥水管理及回收:

  • 使用至藥水沒效力後即當廢液回收
  • 2 Bath Fixing 

"An extremely efficient method of fixing film or paper is to use the two bath fixing technique. Make up two separate fixing baths of the same solution volume. Fix the film or paper in the first bath for half the recommended fixing time and then transfer them to the second bath for the remainder of the time. Continue to work this way until the capacity of the first bath is reached, then discarded it and replace it with the second fixer bath. Prepare and use a completely fresh second bath. Repeat this process as required with the result that the film or paper is always thoroughly fixed by the relatively fresh fixer in the second bath."

Ref: FACT SHEET, RAPID FIXER, ILFORD @ http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

  • 用完即丟 (oneshot use): 最浪費卻也是最新鮮的用法

 

定影不足?

  • 定影不足的影響可以重新泡到定影液中, 定影直至你滿意為止

 

 

Kodak TRI-X 的紫色問題(purple dye): 

  • 可能是定影不足
  • 可以用水洗掉, 水洗久一點不會影響影像

 

定影時間對影像的影響:

  • 殘留銀: 定影不足的底片會有銀殘留的現象, 目視雖無礙, 但過多的殘留銀對底片的長久保存是一種傷害 
  • 定影過頭: 定影過度會對底片有減薄作用

 

 

 

 

 

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