A friend once made a dark slide out of a sheet of brass. For a smaller format film holder.
A friend once made a dark slide out of a sheet of brass. For a smaller format film holder.
Michael, you really have to pay attention to how much pigment is used in the material. Normally there may be 1-3%, but you can get 10% pigment ABS which is specifically designed for light-blocking. You can it in colors other than black (white, for instance). RTP is a common source for this type of ABS. Sounds like you might have gotten the wrong type of plastic.
That's actually good to know, because I was going to reach out to them about making new dry plate holders. Sounds like I don't have to bother. If they can't make dark slides, then they can't make plate holders, either.Originally Posted by Marky
-Jason
Newly made large format dry plates available! Look:
https://www.pictoriographica.com
Thanks for the info. This is why we share pertinent information on the topic of the day. What I learned from my iteration into the world of plastics is that I was completely out of my league floundering with attempts at finding the correct light tight properties at the desired material thickness. Even the quasi experts I engaged in this process let me down.
What we do know is that if we approach this situation as a collective body the solution has a higher degree of favorable resolution. What I gleamed from the Intrepid dialog was that they claimed to have researched and in fact found the correct material from which to make dark slides from and had a pallet of it that they purchased in a video I saw a while back. If they are not doing anything with the material I wonder if they could part with some of it or share with he LF community the specs of it and where they acquired it?
I would also think that the collective body here may know where we could contract a company that could cut a template dark slide for us and what it would cost for these services? I have a dozen brand new Lisco 8x10 holders that I would like to match with a beefier dark slide than what they came with and would easily purchase three dozen replacement dark slides by myself.
And I have 8x10 and 11x14 holders with metal darkslides -- definitely heavier, but no worries of light leaking thru them! Tough sonsofaguns, too.
"Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China
Yep, this is all good information and I think a solution would be great for our community for the following reasons- 1. plastics age (and not in a good way), and 2. No one is manufacturing the slides which are the part most prone to breakage in film holders anymore. I work in a chemistry lab that deals with polymer and materials-based research (although admittedly I hang on the liquid side of the discipline), so I brought in a piece of broken dark-slide this morning and have the following to contribute based on some instrumental and optical data. Looking at IR spectral results for the material and comparing the results to online libraries, it appears dark slide plastic material is a blend of polyvinyl acetate, polyethylene (about 4:1) and a small amount of polyvinyl chloride. Looking at a fracture surface under a microscope, you can see the material likely has carbon black reinforcement and is a cast (vs extruded) material. The carbon reinforcement, if I am correct will make the material stronger when cast, but likely helps with the light-fastness as well. What this says to me is that dark-slide plastic material was more than likely a custom cast blend of polymers that were likely custom made to supply the film-holder industry and likely if there was another market the material was made for, it might be hard to identify. Odds are that it is no longer manufactured since no one is actively making the plastic type filmholders anymore (am I correct with this statement?). Short of identifying the manufacturer and getting them to make more material, our only option for finding a replacement might be identifying another material that is commercially available that has the properties we need to keep the film protected from light and operate smoothly in the holders we can find used. I guess Ill bite the bullet and get a few things and see what I can find out- in the mean time, I like the idea of the community contributing anything they might know that works or not so we can come up with a decent solution (that ideally isn't expensive).
Wow. That is great Eric. Having access to those analytical resources is amazing and a thoughtful way of honing in on the process of scouring the market for an alternative material. I think it is safe to say that the company that produced Fidelity / Lisco holders is long gone and likely any internal technical reference assistance that they could be extracted from them is gone also. Is the same material used for all size holders 4x5, 5x7 and 8x10?
I sent a note to Intrepid Camera Company this morning inquiring about any assistance they could provide since it was pointed out earlier that the film holder segment of their strategic business development plan is being effectively displaced by other projects and/or business plans as the company goes through the arduous process of the allocation of their time and resources.
Earlier online videos and comment documented that Intrepid had researched a suitable dark slide replacement material. I requested some business transparency to the material and vendor from which this material was procured (you just never know until you ask) but even a sample of their material for a test as Eric did with the original dark slide material would be a great confirming analytical data point.
I see the steps in this process as: 1) finding the correct material to make the dark slides from and I realize this could take some time, 2) securing a place to procure the material from as well as the costs, 3) find someone who has the capability to cut these for us (could be a CNC process or someone handy with a template and a proper router bit, 4) coming up with a net sales costs per dark slide and 5) assessing the aggregate demand and packaging this up to get the product cycle completed and to the customers.
Daniel Stone on this forum has a business where he provides products to the LF community online. Since he is already set up for this venue I would toss out his name as a person who may be willing to be the point person having already been set up to do this.
I am just looking for the most efficient way to get this project in the done column so more photographs can be made now and down the road.
Last edited by Michael Kadillak; 19-Sep-2018 at 13:22. Reason: typo
I am talking to one workshop here. The owner is away on a business trip to Europe and the US now, and I hope to have some information by the middle of October.
Kumar
Max Grew (founder of Intrepid) actually shared that info:
http://www.largeformatphotography.in...20#post1432920
Thanks Marty. I remember the video just could not place it. Does FR4 or High Carbon ABS register with anyone relative to a specific product here in the US that someone could chase price and availability? I would think that acquiring aluminum and anodizing it black would be the most costly alternative but this is just a conjecture on my part with no facts to back it.
It looks to me like therr might be some confusion here regarding the term “dark slide”. In some countries this term refers just to the flat black that sheets, often with handles of some type, that are used in film holders. In other countries it appears the term is applied to the entire assembly, hence the term “double dark slide or DDS.
I could be wrong, but I believe what Intrepid have been having trouble with is manufacturing the complete film holder, not the dark slide itself.
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