Safelights

[gray1720]

As part of my Blue Peter-style darkroom (nearly there now)I've got two safelights I picked up, one with an Ebay purchase and one that fell off a passing workplace. One is a Patterson, the other has an Ilford 915 glass in it. Both are fairly red. I seem to recall that the correct safelight for multigrade paper is orange. Am I going to be able to use either of these, or do I need to screw my soul up and actually spend some money?

Thanks,

Adrian

[MJ_Warner]

I would have thought it's a case of try it and see, it depends on the paper and the distance and brightness of the safelight.

It's always amusing to see safelights on television, it's almost a photographic cliche. They will be developing film in a developing tank in a darkroom lit by an orange safelight. On one of the CSI programmes last night two of the characters were examining dried prints under a safelight... But then when they show an image through a camera they don't seem to obey normal optics as the image isn't inverted.

[huwevans]

If you work quickly and don't leave paper out under the safelight for very long then you may be fine. But bear in mind all you need to do to test the light is sacrifice a single sheet of paper (not even that - just a test strip will do). And sensible darkroom practice requires that you do that anyway, so you might as well give them a try before commiting more funds.

[frank1]

I've always used red safe lights and multigrade papers together without any problems.

[beejaybee]

Both are fairly red. I seem to recall that the correct safelight for multigrade paper is orange. Am I going to be able to use either of these, or do I need to screw my soul up and actually spend some money?

You'll very likely be OK. But try with a small offcut of paper, leave it lying near the enlarger but with the enlarger switched off for ~5 mins then develop as normal, it shouldn't be fogged to any significant extent.

[Zou]

My red safelight has a message on the box saying that 1.5 metres is the closest 'safe' distance to position the lamp from the paper.

[gray1720]

Thanks everyone, I shall suck it and see. No doubt I'll be back to moan if it goes wrong. I'm looking forward to getting my hands dirty again!

Adrian

[SUNSHINE]

I have a velux window in my darkroom ~ To make a very effective safelight, I simply stuck some red sticky~back~plastic (fablon, other products are available!) It works very well, even on the most sunny of days. I also have a small round red safelight fixed to the wall and an orange one near my developing tray. I've never had a problem with fogging even with this Heath~Robinson set~up.
The only way to find out is to test your set~up.
Have fun,
Jo

[Manofolympus]

The usual test was to put a coin on a piece of paper, leave for about double the time you anticipate the paper being in that position and then develop. If you can see the outline of the coin the paper is fogged. I was also advised to repeat the test where the enlarger is and where the dev dish will be-as it is quite possible to fog the paper in the developer!

[taxor]

The coin test is a good idea for testing the 'safeness' of safelights, but bear in mind that paper is substantially more sensitised to stray light after exposure. The best test would be to expose a piece of paper under the enlarger such that when developed, produces a just visible tone. Expose another piece of paper for the same time and then, before development, do the coin test.

[gray1720]

After all that advice, I have now found an Ilford 902 glass of the right size in a bin (Amazing what you can find when the Stores dept is having a cleanout!). Now all I need is a wet weekend (no cricket or gardening) and to have written 7500 words on Victorian funerals, and I will have time to sit down and work out what I still need for the drakroom... Must be nearly there, though!

Adrian

[Malcolm_Stewart]

The coin test is a good idea for testing the 'safeness' of safelights, but bear in mind that paper is substantially more sensitised to stray light after exposure. ...

I've used the coin test, but I'm afraid I don't understand the aspect that the paper is more sensitive after exposure to the enlarger - can you explain how the paper knows what time it is?

[Manofolympus]

The coin test is a good idea for testing the 'safeness' of safelights, but bear in mind that paper is substantially more sensitised to stray light after exposure. ...

I've used the coin test, but I'm afraid I don't understand the aspect that the paper is more sensitive after exposure to the enlarger - can you explain how the paper knows what time it is?

It has to do with characteristic curves of light sensitive emulsions. A film or paper builds up density on exposure to light in a non-linear fashion. If this is plotted on a graph it gives an s-shaped curve. At very low levels of exposure there is little or no response from the emulsion-it must climb the toe of the curve before achieving any density. You therefore require what is known as a threshold exposure to do this. Lightly pre-fogging the paper moves the density up the curve to where a small increase in exposure creates a noticeable increase in density-hence, in effect, the paper is more sensitive to the effect of an unsafe safelight-although the actual emulsion speed hasn't changed. This problem is most likely to be encountered if the safelight is too close to the developer dish, since paper isn't usually left lying round the darkroom after exposure.

[apochromatic]

The Ilford 902 ,light brown, is fine for 'most' papers including multigrade varieties but you must use a red filter for high silver content and, typically, chlorobromide papers. (This is a rule of thumb because there is a one chlorobromide multigrade paper.) The comments that have been made about checking the fog level are well worth doing when you first set-up as even a red safelight, if loaded up with too bright a lamp, will cause some fogging.
You will see if there are any holes in the coating too which you can cover with some opaque metal tape.... where exactly is this bin??!!

[taxor]

The coin test is a good idea for testing the 'safeness' of safelights, but bear in mind that paper is substantially more sensitised to stray light after exposure. ...

I've used the coin test, but I'm afraid I don't understand the aspect that the paper is more sensitive after exposure to the enlarger - can you explain how the paper knows what time it is?

I'm not too sure of the mechanics of it, but the previous poster hit the nail on the head. Exposing paper to threshold removes the 'inertia' that all papers possess. Therefore, any subsequent exposure, image forming or otherwise, will record as tone. It is the principle behind paper-flashing. I once did the coin test without pre-exposing the paper (this was with a red safelight) for at least 10 minutes - it could have been longer. No fogging was apparent.

[spinno]

can you explain how the paper knows what time it is?

it's got it writted down on a piece of paper....
what time is it Eccles

[Malcolm_Stewart]

can you explain how the paper knows what time it is?

it's got it writted down on a piece of paper....
what time is it Eccles

Brilliant! It's many years since I heard that first time round. (I was gently trying to point out that paper can get fogged before the main exposure, as well as afterwards.)

[spinno]

when I used to do b/w it was alleged that I fogged the paper during exposure......can't think what they mean...

[DaveS]

My darkroom has a 4' orange fluorescent light about 6' from the enlarger on teh ceiling. I'ts very effective and I've not seen fogging on multigrade.
The lamp is one I got from Silverprint ages ago.
Dave

[AJUK]

I use a bicycle tail light.