My 1st paper emulsion & some success

[tim_bessell]

I pretty much followed D. Ross's formulas with some changes to suit my own workflow and availability of materials. I omitted the KI because I wanted to see what the effect was. And since Everclear is not available in NYS, I used Bacardi 151, ummm rum flavored emulsion.

I test print shows almost all the steps on a Stouffer step wedge, a very long scale; interesting! Developer was Ansco 130 1:1 for 2 minutes. I am going to experiment by adding KBr to get the contrast up. Paper is Arches HP, coated with a blade I constructed out of 1/2" plexi-glass.

The blade is shaped like a trough inside and holds the paper flat just ahead of the stainless blade. It was surfaced on a thick plate of glass with 220 grit sandpaper and water; it's very flat. The blade is a 6" stainless ruler (good enough for now) and is clamped in the slots you see in the image. Two stainless screws squeeze the slots closed to hold the blade.

I need to make the blade out of 1" plexi so it will hold more emulsion. Right now 10 mL is the max.

Also attached is a quick graph of its curve.

 

[tim_bessell]

Should add that I used La Baleine seasalt from the Med.

 

[Kirk Keyes]

Very nice job!

I really like your blade design - I've been thinking of something very similar in plastic.

 

[tim_bessell]

thanX Kirk.

The blade is an improvement over my first design for paper use. The first blade had a space of about one inch between the body and the steel blade. It was easy to see that if the paper had any buckles or bulges, it would not maintain a consistent gap under the blade. Placing the blade closer to the body was a vast improvement.

Before I surfaced it on sandpaper, I assembled the whole blade and snugged up the screws to account for any stress induced deformities. It literally sticks to the plate glass I coat on.

 

[Photo Engineer]

Tim;

Very nice job in blade design and emulsion making. The step scale looks pretty good but a little low in contrast.

Which emulsion did you make?

PE

 

[Kirk Keyes]

The first blade had a space of about one inch between the body and the steel blade. It was easy to see that if the paper had any buckles or bulges, it would not maintain a consistent gap under the blade. Placing the blade closer to the body was a vast improvement.

Are you saying the bottom of the well was about 1 inch and that you decreased that distance in the second well?

How did you do the machining on the well? It looks very nice.

 

[tim_bessell]

Tim;

The step scale looks pretty good but a little low in contrast.

Which emulsion did you make?

PE

Yes, I guess it is low in contrast, if you consider the dMax is only 1.63. But here is the kicker. I have printed a negative that was made for a Kallitype and it looks pretty good for a first, quick, and dirty attempt.

As I mentioned above I would like to experiment with the developer to try and adjust contrast to suit the negative I wish to print.

Do you think that's possible?

The emulsion is Denise's 1A from the Light Farm without add KI.

... and thank you for your comments.

 

[dwross2]

Hi Tim,

Fantastic work!! I think your step tablet results look great. And, very clever coating tool.

I am particularly happy to see you adapt an emulsion recipe. I would love to hear all the details -- if you are willing to share. This is the way we'll grow the art and technology. In addition to anything you can post here, I will be delighted to publish your work on The Light Farm. Again, congratulations!

Denise Ross
editor@thelightfarm.com

 

[dwross2]

Tim, 'Hi' again,

Our responses crossed in the air. Yes, TLF paper emulsions (i.e. 'old' style emulsions) are very sensitive to different developers. You will be able to exercise quite a bit of control that way - not just contrast, but also color to a certain extent.
d

 

[tim_bessell]

Are you saying the bottom of the well was about 1 inch and that you decreased that distance in the second well?

How did you do the machining on the well? It looks very nice.

If I get a chance I might draw it up with dimension real quick in SketchUp and post the file.

It's a little difficult to machine because it heats up and melts pretty fast, clogging up your tools. Drilling and tapping with water works well, but not feasible on a table saw or band saw. Files work and scrapers give a almost perfect finish.

In the end I will have one made of all stainless i think.

 

[tim_bessell]

Thanks Denise, that's just what I wanted to hear!

It may be several days before I can post the results of more testing, but I certainly will.

thanX again

 

[Photo Engineer]

Yes, I guess it is low in contrast, if you consider the dMax is only 1.63. But here is the kicker. I have printed a negative that was made for a Kallitype and it looks pretty good for a first, quick, and dirty attempt.

As I mentioned above I would like to experiment with the developer to try and adjust contrast to suit the negative I wish to print.

Do you think that's possible?

The emulsion is Denise's 1A from the Light Farm without add KI.

... and thank you for your comments.

Tim;

The KI might boost contrast, or the contrast might be low due to the type of salt that you used. Sea salt often has other positive ions that can affect the grain type (good or bad).

The amount of silver coated is also critical to contrast and dmax, and that might be another source of the low dmax and low contrast.

But, as you say, it makes good pictures and that is what counts.

This is a takeoff on an early pure chloride emulsion without the active gelatin so that is another factor in speed, contrast and dmax.

If you wish to raise contrast, adjust the gap (undercut) in your coating blade. With that formula the gap can be from 5 mil to 10 mil and as you go up, contrast and dmax will go up due to the rising level of silver.

If you cannot get everclear, you will find that i-propyl alcohol will work as long as it does not have any of the denaturing ingredients that cause it to become cloudy when added to water.

PE

 

[tim_bessell]

thanX for the ideas PE.

I did understand that potassium iodide would raise contrast and that is why I omitted it as a final addition. That and my interest in chloride emulsions.

The speed is pretty fast, my exposures with a 40 watt bulb, 32 in. from the print frame are 16 sec. Could almost be an enlarging paper.

Right now I am using an .008 gap on the blade; earlier attempts using .005 and .006 gave me very uneven coatings. Of course, you learn and modify your methods as you go to get results you want. So I am still in the very early stages of sorting out the basic techniques.

 

[Photo Engineer]

My exposure time is less than 1/2 that with about the same conditions.

By tests, my paper is 5 stops slower than enlarging paper on-easel.

As for the uneven coatings, did you use any Photo Flo? Lack of a surfactant can cause some sever problems in coating. Denise uses Photo Flo 600 and I use Photo Flo 200. They differ by a factor of 3 in concentration and one uses EG, while the other uses PG for lower toxicity (PF 200). I use PF 200 due to the lower toxicity and also the fact that I can use 3x the amount and this leads to better accuracy in repeat experiments. It is hard to measure a half drop.

PE

 

[Vaughn]

PE -- I use Photo-flo 2100. Anything I should be looking out for with that one?

Vaughn

 

[Photo Engineer]

PE -- I use Photo-flo 2100. Anything I should be looking out for with that one?

Vaughn

It is merely a matter of EG vs PG and toxicity and also the ability to measure tiny quantities.

PE

 

[Vaughn]

It is merely a matter of EG vs PG and toxicity and also the ability to measure tiny quantities.

PE

Thanks, PE -- I should have looked it up first.

I mix 7 oz. with water to make a gallon of stock solution, then the students take one oz. of the stock to make a gallon of working solution. Very strange stuff.

Contains OCTYLPHENOXYPOLYETHOXYETHANOL, which according to the MSDS, does not sound too bad (keep it out of the eyes and the concentrate off the skin.) Also, POLYETHYLENE GLYCOL -- I assume that is the PG you referred to.

Vaughn

 

[Photo Engineer]

PEG = Polyethylene Glycol but PG can equal Propylene Glycol and PPG is Poly Propylene Glyol. The Ethylene derivatives are more toxic than the Propylene derivatives. EG = Ethylene Glycol. Propylene derivatives are safe even as food additives but the Ethylene derivatives are deadly poisons and cause kidney failure.

I am not sure how the polymers stack up vs the monomers of these glycols regarding overall toxicity.

PE

 

[tim_bessell]

Coating blade rough drawing w/dimensions

I used Google SketchUp to draw the coating blade I fashioned from 1/2" plexi and stainless steel. I am attaching a jpeg which is a little large so you can see the general dimensions. I am also attaching the SketchUp file ( fingers crossed.)

The drawing only shows the plexi-glass body, it would be 2 complicated to draw screws and the 'blade' is just a cheap 6" stainless rule.

Several notes:
You will notice a small hole at the end of the slot that houses the blade. This is to prevent the plexi from cracking as the screws are tightened to hold the blade in position. I drilled these holes first and then sawed the slot to the hole on the bandsaw. I used 10-32 stainless steel button head socket screws. The holes for the screws are tapped just on the bottom, longer section so when the screw is tightened the plexi is squeezed to clamp the blade. Be sure the blade doesn't touch the screws or it may move as the screws are turned, defeating the purpose of the design.

Kirk asked how far the blade is from the body. ~3/64" Of course, I do a lot of eyeball engineering; build to suit.

SketchUp is free! Look for it on Google.

I guess I can't upload the .skp file, so if anyone wants it just suggest a method to make it avialable.

 

[dwross]

I tend to avoid drinking darkroom chemicals, or, breathing deeply as if we were talking about fresh apple pie (although I have to fight the temptation with fix -- yes, I'm one of those ).

I actually don't use particularly small quantities of PF600, but it does bring up an important topic in emulsion making. There are many chemicals that are used in very, very small quantities, especially when you scale down for home darkroom-sized recipes. The solution to the problem is to make a solution, i.e. mix a quantity of the chemical that can be accurately weighed with your particular weighing apparatus with water, most easily 1 liter, and then add the number of mls of the %-solution that will give you the miniscule amount called for in the recipe. A Google search will give you all the details you could possibly need, or see Steve Anchell's The Darkroom Cookbook (Disclaimer: Steve is a friend. Still, he's written a great book that I wouldn't be without.)

d

 

[Kirk Keyes]

Tim -

Thanks for the sketch. Could you email me the .skp file to kirk@keyesphoto.com? Actually, I bet if you email it to Denise as well she'd be happy to put it on the Light Farm website.

My local plastics house has 1" thick acrylic (as well as the 1/2" like you used here). For your Rev. 2 coating blade, are you planning on simply extending the dimensions upward 1/2"?

You said "plexi" - is that the acrylic version of "plexi" or the polycarbonate (actually real) "plexi"? I can easily get acrylic at 1" but polycarbonate only up to 1/2".

Did you think of HDPE? Or VHMW or even UHMW Polyethylene - it's supposed to be similar in many properties to Teflon - low coefficient of friction, chemically resisitant, resisitant to abrasion. And can get them all cheaper locally than the acrylic stock.

Kirk

 

[Kirk Keyes]

There's a lot more hazardous things to worry about than the type of glycol used in a product... They are all so low in toxicity that it's a non-issue - for me. It's like worring about the differences in toxicity between KCl vs. NaCl.

 

[tim_bessell]

Kirk,

File sent!

I'm not real sure, but I think I used Lucite acrylic. There is no printing on the protective paper cover on the left over piece I have, though there was on the part I used. In its current form, this blade can only coat a 5 1/2" x 15" area. Not very economical if I cut a 6" strip off a standard 22x30 sheet of watercolor paper where I would like to get 3 5x7's.

I have some UHMW plastic in 3/8", it's not very rigid, it is very slippery. If I go the plastic route I need something that can be worked with woodworking tools and not need a special grind on saw blades and drills.

 

[Photo Engineer]

There's a lot more hazardous things to worry about than the type of glycol used in a product... They are all so low in toxicity that it's a non-issue - for me. It's like worring about the differences in toxicity between KCl vs. NaCl.

Kirk;

Yes, I can agree to an extent.

I try to keep the entire facts before the audience though because not all of them are chemists as we are.

The issues of the type of glycol and the concentrations which cover a range of 6x from Photo Flo 200 - 1200 makes a big difference in work flow due to the need to make up stock solutions and juggle amounts used. The different glycols take different concentrations in their own right.

So, it is not straightforward.

PE

 

[tim_bessell]

A comparison test

I tried adjusting the bromide & carbonate level of Ansco 130 to get a little more contrast out of this emulsion. Need to experiment some more, but I did get a little more contrast.

Here is an image of two prints made with the same negative. On the left a Kallitype toned in gold, printed about 6 mo. ago, and on the right the emulsion I am working with, mentioned in this post.

The prints where scanned at the same time.