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I’ve never had a problem with calcium hydroxide dust but if you are concerned you can use silica gel.

See Mike Robinson’s post on this subject.

Wiping the polish residue from the back of your plate will prevent getting any into your fuming box. Vacuuming the fuming box drawer and the inside of your plate holders frequently will prevent dust deposit there.

To examine the developing plate inside the desiccators you need a directional red light you can shine on the plate at a low angle. A regular flashlight with a rubilith filter taped to the end or a red LED flashlight work well.

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Dafna,

It looks like you have a partial image on the first and last plates.

First of all, assuming you fumed at 20C, your Iodine fuming may be too long.

When the plate coating is very thick it can obscure the image, making it hard to see under red light.

Ten seconds over iodine (to yellow with a trace of red) followed by 10 seconds over bromine (to a redder yellow) should be enough. More time, up to 20 seconds over bromine, may be required if the quick does not contain enough bromine.

After the bromine, fume the plate for 5 to 10 seconds over the iodine under dim white light (to a violet rose) and then for 2 to 5 seconds more over iodine under your red safelight.

Fumed plates will not keep for a week. After a day spots and swirls start to appear.

Silver iodide and bromide are very stable in the dark and not prone to loss of halide or “out gassing”.

Only exposure to stronger halide gasses like chlorine or fluorine can displace the bromine.

Possible adsorption of silver halides by residual lampblack or other polish residue left on the plate is a likely cause for spots.

Some say old plates can be refreshed by more fuming but I think it’s best to start over.

Lower storage temperatures and humidity will slow this aging process but eventually time will take its toll on the plate.

Another possibility is that the plates have come into contact with some moisture although that seems less likely in Israel. Maybe there is some water in your iodine or mercury. Try putting some silica gel in your vacuum desiccator.

Good luck,

John

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his article David Burder states that he once tried silver spoons for Dags.

I believe one of our site administrators started out using solid silver plates but when he switched to electroplated plates he reported that they were faster.

This may be due to the fact that the harder silver plate was easier to polish.

Rio Grande @ http://www.riogrande.com/Category/Metals/104 sells both clad silver in 18 gauge, 3 inch wide strips ($34 for 4inches) vs. $183 for a 3×4 inch sheet of 18 gauge solid silver. The silver is 92% sterling silver and the filled silver is on a 90%Cu/10%Zn base.

[photolytic]

For wholeplates, use enough mercury to cover the bottom of a 5 to 10cm dish. The dish should be deep enough (1cm) to prevent the mercury from sloshing out when you move the desiccator. To prevent the dish from sliding around, nest the dish in a thin layer of silica gel on the bottom of the desiccator.

If your mercury has a grey oxide coating on the surface, filter it though a funnel made from a small (5cm) circle of filter paper folded in quarters. Poke several pinholes in the bottom of the funnel to allow the mercury to flow through. The oxide particles will stick to the sides of the paper funnel. To faciliate flow of the last of the mercury at the bottom of the funnel, gently pick up the funnel wearing latex gloves, fold the top of the funnel to close the opening, and squeeze from the top until the last drop of the mercury is filtered. If there is still oxide left in the mercury, repeat the filtration with a fresh paper funnel.

To prevent lampblack or other polishing residue from accumulating in the mercury, wipe the back of your Dag plates with a tissue before fuming.

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Yes, the vacuum you need is on the left, inside your red circle. Any vacuum higher than 685mmhg will also work but timing development is more difficult since the air pressure needs to be restored slowly to avoid spraying dust or drops of Hg on the Dag. The pressure restoration time depends upon the volume of the desiccator. Always face the Dag away from the desiccator inlet to minimize Hg droplet spots.

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Dafna,

You are right.

The units on your gage are 0 to -760mm (-29.92inches) of mercury which is a “perfect” vacuum.

A vacuum of -27in or -658mmHg is best for vacuum cold mercury development.

To use the gage turn on your vacuum pump and open the ball valve below the tee.

Wait until the gage needle rotates counter-clockwise almost to the -700mm position.

Then while the ball valve is still open and the pump still running, close the valve on the top of the vacuum desiccator (not shown) and disconnect the rubber tubing from the desiccator so you can place it in a large box away from the light during development of the Dag.

At this point you may turn off the pump.

Digital vacuum gages are also available.

They are somewhat easier to read.

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There is no reason Bdag images should harden with time as they contain no mercury.

I’ve had some for several years and they are still fragile.

Barger and White attribute the mDag hardening process to a change in the mercury to silver ratio of the Amalgam. Over the years the amalgam continues to lose mercury through evaporation so analysis of very old ungilded Dags showed there was very little mercury left in the image.

Dentists who used to use Mercury Amalgam to fill caries were also familiar with the hardening process. The process is speeded up by heat normally used in the Dag drying process.

Ken you should try drying an MDag without heating to see if the same hardening occurs.

Wash the water off the Dag with alcohol first and let it dry at ambient temperature.

[photolytic]

Sorry but the ISO speeds on the plate are in the wrong order.

The following figure shows the speeds in the correct order.

 

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I exposed a 2nd yellow Becquerel plates to a grayscale at several ISO speeds from 0.005 to 0.022 and developed the image under rubilith.

The Best contrast was obtained at ISO speeds of 0.008 to 0.014.

 

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[photolytic]

Congratulations Mate. I think the tones are good.

How many layers of red film did you use?

Can you place an incident light meter under the film and measure the light intensity?

Then compare this to the light level you get with Rubilith when it arrives.

Perhaps the light intensity is more important than the exact color to prevent fog on the plate.

John

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HI Dafna,

Yes, I am John Hurlock and I live in my Dagcave with my faithful four footed sidekicks Squeaky, Boadicea, and Lisel. No great secret here since I signed my name in the second post of this topic but thanks to Gregory for clearing up any remaining confusion.

I sometimes use the term torr which is a measure of absolute pressure in mm of mercury commonly found in scientific articles, rather than the term mm of vacuum since the latter requires some prior knowledge that the standard atmospheric pressure here on Earth is 760mm of mercury. Those of you who have been following the recent presidential debates can appreciate the confusion among future Daguerreotypists living on moon base Gingrich.

The quotation “24hours at 25 torr” is a bit misleading, since only 1 hour at 25torr is enough to develop a Dag at 20C.

Gregory is correct in that only a few drops (0.2ml or a little over half a gram) of liquid bromine in 200 grams of calcium hydroxide is enough to turn it a light orange color, but unless your fuming box is sealed very tightly, you may need to replenish this weekly to maintain constant fuming times.

Also don’t store your bromine and/or iodine fuming boxes in the same hood where you are developing Dags as even a small amount of halogen is enough to erase the latent image of a Dag. Yet another reason to rely on a well sealed fuming box rather than a hood for long term storage of fuming mixtures.

John Hurlock

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Dafna,

The desiccator in the pic looks as if it has a small Teflon valve at the top. These tend to leak as the Teflon is soft is soft and deforms under pressure. Even if the valve actually has a glass stem, the width of the greased seal is rather narrow and begins to leak after a few turns of the valve. Better to get the “German” or Pyrex design with large rotating glass valve collar valve on top of the lid. These need greasing periodically as they tend to tighten up when the grease film spreads out with use but they leak less than the smaller valves.

http://www.ebay.com/itm/370470077386?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

I should explain that all desiccators can leak slightly even through a well greased ring seal. A 24 hour seal is not absolutely mandatory as the Dag development rate depends mainly on the maximum (initial) vacuum and the developing time rarely exceeds 3 hours at 20C.

[photolytic]

Dafna,

I’m not familiar with the Chinese glass dessicator but my main concerns would be the thickness of the glass and the type of seal. Glass on glass is better than a telfon seal.

A picture would be very helpful.

John

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$50/gram is the equivalent of $100/gram of gold metal or $3110 USD / troy oz.

That is a little less than twice the current commodity market price for gold.

Artcraft Chemicals in US is selling gold chloride for $48 USD /gram.

http://www.artcraftchemicals.com/products/products-page/general-chemistry/a-m/gold-chloride-solid-part-1700/

I don’t know if they ship to Europe but first class mail may be possible.

[photolytic]

Concerning the use of varnish on Dags:

This subject was discussed on Jonathon Danforth’s shinyphotos.com on June 8 2008.

Any substance that you put on the surface of the Daguerreotype will have a different refractive index from air and will change the way the image particles reflect and refract the light. I have coated Dags with the gum Sandarac varnish used on ambrotypes, and although it reduces the brilliance of the image considerably it does protect it from abrasion. Because this varnish shifts the wavelength of the reflected light away from the blue region of the spectrum, the varnish will also transform a fugitive or solarized blue image into a warm brown one.

The cost of gilding with gold chloride, currently running around $50/gram, is still only a little over $2 USD for a wholeplate. According to our expert Daguerreotypist from Russia, Bailun, you can also gild with platinum Chloride but I’m not sure of the relative costs.

Compared to the high cost of plates, mats, and cases, the gold is not too high.

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Javi,

Nice images,

Yes a random orbital buffer can be used at low speed in place of hand buffing.

You need more sponge applicator pads though. One for rouge, a second for lampblack, and a series of clean pads to remove the reside from the plate after steps 1&2.

Last minute buffing of the inverted plate (face down)on a clean hand buffing pad can be used to remove any dust or velvet lint just before fuming. Keep your buffing pads in sealed plastic bags when not in use to prevent dust contamination. Warm the pads with a hair dryer before use to remove traces of moisture.

Crown Graphic cameras are nice and relativly cheap ($300USD on EBay).

[photolytic]

Javi,

As you know, the intensity of light from a lens diminishes as the square of the distance from lens or in other words the area covered by the image it casts. Hence your exposure should be proportional to the square of the ratio of the (close-up) lens to plate distance divided by the normal focal length of the lens at infinity.

EX: for a 100mm lens extended to 150mm, the exposure time should be extended by 150mm/100mm squared or 2.25 (a full stop).

Brian May of Queen, a Daguerreotype collector himself, would be amused to learn that he has become part of the process itself.

Wash the plate in flowing tap water, being careful not to place the plate itself under the spout to avoid damaging the delicate image. Then, holding the plate at an angle, flood the upper edge with a stream of distilled water so that it flows off the opposite edge. Do this several times(3)until all the tap water has been washed off. At this point the water should be repelled by the surface of the plate and flow off completely when chased by a stream of hot air from a hair dryer.

Happy Daging, John

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Javi,

Thanks for the update. Your dag stll looks slightly dark but the tones are good.

The center image looks to be the 3min exposure. Is that correct? Over exposure can block the highlights, making them look out of focus.

Ten times is about max for a plate with 13microns (.0005in)of initial silver plate.

For a 25micron silver plate you can get about 20 images before it wears out.

All this depends upon how agressive your polishing technique is.

If your polishing is sufficient and you have enough silver left on the plate, you should have no stains or scratches on the plate. The stains may be a sign that you have buffed through to the copper. Those dark wavy lines around the edges of your plate indicate the copper is closer to the surface. The plate can still be used for experimenting.

I would suggest you try a more agressive polishing technique such as randon orbital buffing, or hand buffing with a courser buffing compound to get rid of all scratches and stains.

What are you using now?

A first cycle magenta fuming may be more sensitive.

Developing in weak shade light takes too long, allowing the latent image to fade. Better to stick with the brighter halogen light if the sun is not available.

The sodium sulfite is added to prevent the oxygen in the air from oxidizing the thiosufate.

If your hypo is fresh (no sulfur odor) and you make up fresh fixer for every plate you can get by without the sulfite.

[photolytic]

Dear MR Javi,

1’45” @ 21C should easily give you a second yellow color if you have enough iodine in your box.

2nd yellow should be OK but Pobboravsky has shown that thicker 110uM plate coatings may be as much as 16 times less sensitive to light (4stops) than thinner 30uM coatings.

Just to be sure that this is not the problem, you should try masking off part of the plate with paper and fuming portions of the plate for 40” to magenta, and for 80“ to light blue and then for 105” to second yellow..

You don’t mention the aperture you are using but even 20min at f/8 might not be enough if the light is less than 13EV. If you have an exposure meter, use it! Despite claims that Dags are only sensitive to UV, Pobboravsky has shown that Dags are also sensitive to light up to blue 450uM so a meter reading is a good start.

Lastly the red plastic may not be as good as Rubylith for developing Becquerel Dags.

You don’t say whether your Dags have no image particles, which indicates underexposure, or that they have a whitish coating, which indicates overall fog.

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Hi Dan and Mike,

The most common moisture indicator in silica gel is cobalt chloride, It is pink or purple in the hydrated form and blue in the dry form. It is possible that the pink color might make it more difficult to judge the level or halogen added from the color of the mixture but this would only occur in the presence of moisture, an unlikely event unless one added bromine water instead of anhydrous bromine liquid. While cobalt salts are carcinogenic when inhaled, the level used here is so low that the indicator silica gel does not have to be labeled carcinogenic even in California. Since chlorine is a stronger oxidizing agent that bromine or iodine there is no possibility that chlorine would be released if these halogens were mixed with indicator silica gel.

Best, John

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Anodizing is a process whereby the surface color of the metal is altered. It is usually associated with aluminum. (aluminium outside the states). It is not a sliver plating process but can be applied to color the surface of silver. It is not desirable for making Dag plates however.

[photolytic]

Hi Li,

I assume you always used distilled water and switched sources.

Perhaps we all need to distill our own water.

I once saw Irving Pobboravsky using water he distilled himself.

Deionized water is ok too but you need to test the conductivity.

We used double (twice) deionized water for critcal work in our lab.

Let some of the water dry on a glass plate and see if it leaves a residue.

Good luck, John

[photolytic]

Hi Li,

I assume you always used distilled water and switched sources.

Perhaps we all need to distill our own water.

I once saw Irving Pobboravsky using water he distilled himself.

Deionized water is ok too but you need to test the conductivity.

We used double (twice) deionized water for critcal work in our lab.

Let some of the water dry on a glass plate and see if it leaves a residue.

Good luck, John

[photolytic]

Hi Li

Using butane is ok but you need to hold the flame further away from the Dag. Heat more slowly.

Use strong lighting and watch for the first signs of steam above the plate then stop heating.

Use an infrared thermometer to check the temp at various points on the plate and don’t let the temp get above 60C.

Good luck, John

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Blowing the plate with the air dryer before fuming should be done on the back of the plate. Most Daguerreotypists use a large rubber bulb to blow particles off the front of the plate. However if you turn your plate upside down during the last hand buff there is less chance of leaving particles on front of the plate. Warming the buff immediately before use with an air dryer also helps. Blowing the plate after exposure but before mercury can be very problematic. If the air contains any moisture the image may be spotted.

Most sheet film photographers vacuumed the inside of their holders before inserting the film to eliminate dust spots. This is also a good idea for Daguerreotypists since the back of a polished Dag plate frequently contains traces of polishing powder which rubs off on the holder. Rubbing the back of the plate with a soft dry tissue will remove most of this residue but not all. Rob McElroy also air blows the holder slides before putting them back in the holder after shooting his Dags.

Since I always develop my plates in a vacuum over cold mercury, I keep a layer of silica gel in the bottom of my mercury chamber underneath the mercury dish to minimize the moisture content.

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