Neg carrier refurbishment

[swmcl]

With a recent purchase of a Durst L138 comes the requirement to refurbish the neg carrier whose black rope at the top has perished and the felt underneath also. Along my journey, I wonder about the glass(es). The guy before me has had a piece of cardboard where the glass was. I'm not sure what was going on but lets just say the cardboard will not be staying !!

So without getting into the pro's and con's of glasses and glassless etc. I'll ask about one concept only...

I assume that if one were to use two pieces of glass to hold the negative with one being AN glass ... if those pieces of glass were a good thickness then the AN rings (being on the side away from the negative) would never be in focus ...

Is it possible to get thick AN glass ? Am I heading in the right direction ?? Should only one piece be thick ?? What sort of thickness would seal-the-deal ??

As a side thought ... what does AN do that a groundglass does not ? Why not make a thick groundglass to sit on top of the negative ?? (Say a 5mm thick ...) Thick glass is not as hard to find as thick AN glass ...

Rgds,
Steve

[swmcl]

It looks as though I got that wrong.

The AN side of the glass is on contact with the neg I believe. So no need for thick glass ...

[swmcl]

OK ! OK !

Its only a flesh wound (in the memory of the dark knight in Monty Python) ... I aint dead yet !

What about a glass sandwich with groundglass touching the neg with Kami fluid ??

[Leigh]

You do not need any fluid.

The AN glass surface touches the back of the negative.

Regular glass touches the emulsion side. No rings.

- Leigh

[Drew Wiley]

If it's actual Durst Anti-Newton glass intended for their carrier, it can be used on both the top and bottom of the neg with no ill effect. The AN texture should be in contact with the film on both sides. That's the way I've routinely done it for decades. If other brands of AN glass are used, it all depends on the quality of the glass and angle of light incidence; and, of course, the glass has to be the correct thickness for your Durst carrier.

[swmcl]

Sorry guys,

I have no glass. All that was in the carrier was some bent cardboard.

The question is - what glass and how much of it is needed.

Any thoughts on using some groundglass on the light side of the negative with some Kami fluid ? (Emulsion always down)

[Bill Burk]

AN glass isn't necessary if you provide some relief from the glass to base surface. For example if you shoot sheet film with a retouching texture, this could provide the necessary breaks of contact that prevents rings.

An old lithographer's trick is to dust the glass with some grains of cornstarch. I'm not sure I'd want to do it with fine negatives, but it worked with graphic arts film for platemaking.

I think groundglass is too much for the job.

[Drew Wiley]

Here in the coastal fog belt, all of the above might be necessary to tame rings. But the inherent flaw of AN powder (corn starch) is that it is both a particulate contaminant getting inside an optical system, and a food source to booklice. Modern AN aerosol sprays don't have that issue, but introduce unhealthy fumes, so should always be used in conjunction with a fume hood. You spray a cloud of it into the air, then swipe your negative through that temporarily suspended cloud to a get a gentle even coating. If you spray the neg directly, you get a mess.