Safelights and Kentmere FB

[Andrew Bartram]

Les

I have used an Encapsulite 4ft tube (red) for some years in my small home darkroom. The level of illumination is superb. I test the safety of the tube once a year by following the Kodak method
1. 1 min strips under safelight
2. expose paper to light gray
3. 1 min strips under safelight

This method is supposed to determine safety before and after enlarger exposure.

I mainly use Ilford paper and both RC and FB show no fogging whatso ever up to 10 mins pre and post enlarger exposure.

Not so with Kentmere Fineprint FB that clearly fogs after enlarger exposure but not noticable on pre enlarger exposure.

When I switch to a wall mounted SL1 safelight no problems - although illumination is less.

Your thoughts appreciated on

a) The Kodak Safelight test procedure I follow
b) Encapsulite tubes and their effect on Kentmere Vs Ilford papers

I can always just use the SL1 of course.

Thanks in anticipation

Andrew Bartram

[Les McLean]

[QUOTE=Andrew Bartram;20288]Les

I have used an Encapsulite 4ft tube (red) for some years in my small home darkroom. The level of illumination is superb. I test the safety of the tube once a year by following the Kodak method
1. 1 min strips under safelight
2. expose paper to light gray
3. 1 min strips under safelight

This method is supposed to determine safety before and after enlarger exposure.

I mainly use Ilford paper and both RC and FB show no fogging whatso ever up to 10 mins pre and post enlarger exposure.

Not so with Kentmere Fineprint FB that clearly fogs after enlarger exposure but not noticable on pre enlarger exposure.

When I switch to a wall mounted SL1 safelight no problems - although illumination is less.

Your thoughts appreciated on

a) The Kodak Safelight test procedure I follow
b) Encapsulite tubes and their effect on Kentmere Vs Ilford papers

I can always just use the SL1 of course.

Thanks in anticipation

Hi Andrew

I'm in London at present and will not be home until 7th Dec when I will post a description of my own testing procedure. However, my initial thoughts are to question the Kodak method you describe. I don't understand why you expose the paper first to enlarger illumination followed by exposing paper to gray light and finally to more one minute strips of enlarger light.

I have always made a test strip using white light to determine the minimum exposure that produces slight fogging (very light gray tone) on the paper. I then expose the paper to be used in the safelight test to the step BEFORE the fogging occurs. This test to determine the flashing time is done in complete darkness. I then place one sheet of paper on the baseboard and a second in the wet bench or the area where the paper is developed, I place two coins on one end of the paper and cover the remainder, after one minute I move the card covering the paper to allow a second row of two coins to be placed on the paper. I repeat this for about 12 minutes and then develop the paper normally. You will see the shape of the coins when the paper starts to fog.

A general comment about safelights. Different papers need different coloured safelights, this is why some of your paper is fogging very quickly. I have at least two different types of safelight in my darkroom for this purpose.

Encapsulite safelights are very bright but they do quickly fog many papers. I did have them in my darkroom for a short time but got rid of them when I realised what was happening. I currently use Ilford 902 and the Patterson domed safelight and find they cover all papers that I use. I have three 8 x 10 902 safelights which provide quite bright illumination, the key being tha the colour temperature of the light is safe. Check the instructions of the paper you are using for they should tell you which safelight is best for their paper.

I'll post a full descrition of my method when I get home.

[Andrew Bartram]

Les

Thanks for that, I didn't really give you enough detail about the safelight procedure I follow but basically I generate a test strip from White through to light grey, noting the exposure time for light grey. This is done in complete darkness. Fresh paper goes on baseboard and cover a strip with card, this receives no exposure. Safelight on and after 1 minute move card along another strip. This continues for 10 minutes.
This part of the test determines the safe time BEFORE any enlarger esposure is made.

The whole papper is then exposed to the light grey fogging exposure (safelights off)

The paper is moved to the wet side and with the card covering strips at 90 degrees to the first part turn on the safelight and gradually cover more strips up to 10 minutes.

The result is a paper that tells me how long the paper is safe BEFORE and AFTER enlarger exposure.

I forgot to add that a 8X10 card mask with a slightly smaller aperture is used throughout on top of the paper with 1 minute graduations marked on. This also gives a paper white reference for comparison.

Having said all that the encapsulite is indeed bright, that's why I like it. Ilford MG RC and FB seem OK but I will test again using your procedure once you've posted it.

Thanks Again

Andrew