Kitchen Lab Emulsions

Oster Handmixer Emulsion

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The Light Farm Low Tech Emulsion #2:
Oster Mixer Emulsion

'Storm Watching'
'I' emulsion made with an electric hand mixer.

Tools and materials needed:

  • Hard bloom photographic grade gelatin.
  • Silver nitrate (AgNO3).
  • Sodium chloride (NaCl).
  • Citric acid.
  • Potassium bromide (KBr)
  • Potassium iodide (KI).
  • Photoflo 600 (or Daniel Smith Acrylic Flow Reducer cut 2:1 with distilled water).
  • Glyoxal.
  • Everclear or similar (keep some in a small atomizer bottle for spritzing).
  • Distilled water (keep some in the refrigerator).
  • Scale accurate to at least 0.1 g and calibration weights.
  • 2-oz amber glass dropper bottles (3).
  • Digital thermometers (2).
  • Strainers: stainless steel tea and gold mesh coffee (2).
  • Lightproof, waterproof canisters (2).
  • Plastic spoons and forks.
  • Plastic condiment cups.
  • Plastic canning (wide mouth) funnel.
  • Small 'rubber' (plastic or silicon) scraper.
  • 10 ml and 100 ml graduated cylinders are very handy or measuring cups or syringes marked in mls.
  • Protective gloves and eyewear.  Old clothes or a mad scientist coat.
  • Oster electric hand mixer with stainless steel whisk.
  • Small plastic funnel and an electric drill with a bit to match the funnel neck size.
  • 5/8" hole punch or similar, paper punch
  • Monoject 412 curved tip syringes
  • Crockpot.
  • Buffet warming tray, or similar, referred to as 'hot plate' in the recipe.
  • Tall French working glasses (21 oz. Luminarc) (2).
  • Canning jars, 1/2-pint size, with lid rings (6).
  • Several baby food jars.
  • Safelight (Red or amber.

The mixer setup is made by punching two holes in the plastic lid.  A paper punch hole is just right for a small funnel and a 5/8" hole lets the whish neck fit in to prevent splash up during the mixing process.

A waterbath is easily made from a crockpot and a tall (21 oz.) French cafe/working glass (or wide mouth quart canning jar.)  The illustration here shows a second jar secured by the lid of the cafe glass (for smaller batches.) The one glass inside the crockpot holds a remarkably stable temperature. (There's a more detailed picture on the previous page.)

The Light Farm Low Tech Emulsion #2: Oster Emulsion

a.k.a. 'I '

This recipe can be adapted for a Hershey's Tornado and  'Warm ♥' can be made with an electric mixer.

Gel A13 g gelatin / 75 g or ml water (Tip: for water, ml is the same as g)
Bloom (swell in water) 1 hr starting with cold distilled water.
Melt to 43°C in a waterbath kept at 43-45°C.

Gel B13 g gelatin / 75 g (ml) water (or: 65 g if coating wet paper).
Bloom gelatin for 1 hour starting with cold distilled water.

Tip: As you assemble your equipment, do a dry run of measurements -table salt or sugar, tap water, and Knox gelatin are cheap test substitutes- to make sure the amounts required fit in your containers at each step.

Have ready:

  • Crockpot waterbath at 52-53°C. (Tip: Keep both crushed ice and very hot water close at hand to keep the temperature regulated, if need be.
  • Assembled Oster mixer with whisk in working glass with funnel ready to be put together.
  • Monoject 412 syringe(s). (Tip: I pre-fill two.)
  • Baby food jars. Plastic condiment cups to weigh out and hold dry chemicals
  • Plastic spoons and forks. (Tip: Wash and rinse everything, even the plastic items straight out of the packaging.  "Too clean" is impossible.)
  • 2 8-oz canning jars, plastic wrap and jar lid bands.
  • Atomizer bottle of Everclear (a lens cleaner bottle, washed with detergent and rinsed once with Everclear before filling; used whenever 'spritzing' is called for.)
  • Lightproof canisters and heavy black plastic (if needed) for storing the emulsion in the refrigerator between stages.
  • Weighed chemicals:
    • 3.9 g NaCl (Sodium chloride) / 12 ml (g) water
    • 5.6 g AgNO3 (Silver nitrate) / 20 ml (g) water
    • 0.5 g citric acid / 10 ml (g) water
    • 0.5 g citric acid, dry
    • 0.6 g KBr (Potassium bromide)

Dissolve NaCl set at room temp.

Dissolve AgNO3  warm to 40°C. (Tip: at no time let silver nitrate touch your skin.)

Dissolve 0.5 g citric acid in 10 ml water warm to 40°C.

  1. Set the working glass in a 55°C waterbath.
  2. Strain melted Gel A through a tea strainer into the glass. 
  3. Add in this order, stirring briskly with a plastic spoon after each addition: NH4Br, 0.5 g dry citric acid, and the NaCl solution.
  4. Combine the warm citric acid solution and the AgNO3 solution. Suck up about 10 ml into a syringe. Hold the rest at 40°C. 
  5. Pull the waterbath off its heat source and place it in a stable surface with a piece of slipstop fabric under it to hold it in place during the mixing procedure.  Put the whisk neck through the 5/8" hole and a small funnel in the small hole.
  7. Touch the tip of the syringe to a clean paper towel and carefully shove the tip into the neck of the funnel in the lid of the working glass (being careful to not depress the plunger).
  8. Turn on the mixer at slowest speed and immediately start to slowly and evenly add the silver solution. (Aim for about a 1 ml/second emptying rate.) This is termed the Precipitation or Emulsification step.
  9. As quickly as possible, repeat the process (either by refilling the first syringe, or using a pre-filled second.  There will probably be a little silver solution still left.  If so, repeat a third time with whatever is left. (It is important to use every drop of solution.)
  10. Continue mixing for about 10 seconds after the last of the silver solution has been added.
  11. Remove the lid and whisk.  Place the waterbath with the glass of emulsion back on its heat source.
  12. Check the waterbath temperature to make sure it's still at 52-53°C.  Adjust if necessary. (Have both very hot water and very cold water standing by to make adjustments.)
  13. Spritz the surface of the emulsion with Everclear and gently stir the emulsion for three minutes with a plastic spoon. (Check the waterbath temperature to make sure it's still at 52-53°C.)
  14. Fluff the bloomed Gel B with the tines of a plastic fork.  Switch to a plastic spoon, and over 2 minutes time incorporate B into the emulsion (i.e. add it to the emulsion with stirring, including stirring up from the bottom).  When it has all been added, stir an additional minute for 3 minutes total.  (Tip: Total times, in the heat and out, are emulsion variables. They are not hard and fast rules, but do take notes if your procedure varies so that you can calibrate cause and effect between makes.)
  15. Divide the emulsion between two canning jars. (Pour through a stainless steel tea strainer. The mixture will be frothy.  You may need to press the emulsion through the strainer with a scraper.  Try to divide the emulsion evenly.  Place a double layer of plastic wrap over the top of each jar and secure with the lid ring. (Tip: You don't want to use the metal lids that comes with the jar. They will react unfavorably with the emulsion.)
  16. Immediately refrigerate in lightproof canisters pre-chilled with a half inch of cold water. (Tip: Every household goods store I've been in sells a version of stainless canister with a snap-down plastic lid.  Place several layers of black plastic — cut up trash bags — between the canister and the lid.)


Preheat crockpot waterbath to 50-52°C. 

Preheat a waterbath on the hot plate to 43°C.

Have ready:

  • Dropper bottle of 1% Potassium iodide (KI). (To make: Mix 1g KI with 100g hot water)
  • Dropper bottle of Photoflo 600.
  • Dropper bottle of glyoxal.
  • Coating tools and surfaces.
  • Precut paper and small pieces of adhesive tape (I tear off about 36 1-inch pieces and line them up on the clothesline over my sink.)
  • Small jar of Everclear.
  • Strainers (tea and gold mesh coffee filters) and plastic canning funnel.
  • Hot distilled water.
  • Wash buckets (one with hot soapy water, one with hot clean water).
  • A second cafe glass (or quart canning jar) sitting in a quart-size glass measuring cup or dish, with room temperature water as high as possible before the cafe glass is unstable.


Melt one jar (1/2 batch) of emulsion: Remove jar from the lightproof container and place in a 40°C waterbath (have the water level at about the height of the top of the emulsion).  Stick a thermometer through the plastic wrap into the emulsion.  When the temperature of the emulsion hits about 38°C, remove the plastic wrap and gently stir with a clean plastic spoon until the emulsion is 41-42°C. 

Strain the melted emulsion through a stainless steel tea strainer into the cafe glass in the crockpot.  Keep the waterbath temperature at 49-51°C.  While constantly stirring with a plastic spoon, add 15 drops 1% KI solution at about a drop per second, stir one minute.  In the same manner, add 12 drops Photoflo 600, stir one minute.  Add 15 drops glyoxal and then spritz the surface of the emulsion with Everclear.  Remove the glass from the waterbath and wipe the outside dry.  Pour into the second cafe glass through a stack of two or three gold mesh coffee filters.  Spritz with Everclear.  Set the water-jacketed emulsion on the hot plate. 

Begin coating. (More about coating here.) (Tip: The waterjacket should warm up at close to the same rate as the emulsion cools.  This keeps the emulsion at about the same temperature during coating. A little experience with your workflow will quickly help you determine your temperature parameters.)

The first coating pass with tell you two things:

1) Is the emulsion cool enough?  If the coating is too warm it will go on too thin and you'll be able to see the dull paper through the shiny emulsion.  Just wait a couple of minutes, give the emulsion a gentle stir with a clean plastic spoon, and try again.  Mark this first sheet because it's not wasted.  It can be cut into test strips when you start printing.

2) Is the surfactant right?  If you see air bubbles or spots (repellency indicators) add another drop of Photoflo 600 and give a gentle stir. 

A few more tips:

  • Tiny bubbles, often in a cluster, indicate that you probably added air during the emulsion take-up.  Have an atomizer bottle of Everclear close at hand and immediately spritz the bubble patch from about 4 inches.  The bubbles should disappear.  If they remain, don't try again.  After the emulsion starts to set, Everclear can leave its own marks on the surface.  Make note of the location of the defect and avoid printing on that area. 
  • Keep a black permanent marker close at hand.  Right after coating, the surface of the emulsion is shiny and any and all defects are plainly visible.  It is a simple matter to make a map along the uncoated edge of the paper to guide your printing.
  • After the paper is dry, and you start to stack the sheets for storage in a paper safe (or light proof bag) triage the sheets.  Start with the 'ugly' ones on top.  These will be your test strips and you'll soon value them.  They eliminate the stress of cutting up perfect sheets for testing ;-)
  • One defect that doesn't show up until printing is "slugs".  If you see them, you'll recognize them.  Good straining all but eliminates the problem.

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