In conversation with: Tim Gilbert of Stearman Press

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Some months ago, Stearman Press released their answer for 8×10 film processing, the SP-8×10 — you can read more about it here on EMULSIVE. I recently had the opportunity to interview Stearman’s chief designer, Tim Gilbert with a view to move past the tech specs and learn about the story behind the SP-8×10. This is the resulting conversation.


EM: The first thing that comes to mind with the SP-8×10 is that the design is completely different from the SP-445; why such a radical change?

Tim: Frankly, we tried a supersized version of the SP-445 for 5×7 sheet film. We thought it would be easier to take small steps before jumping to 8×10 and launched it as a crowdfunding campaign. While the prototype worked — well mostly worked — it failed to meet the funding goal.


People kept asking for something larger so we tried again with the SP-2810, hoping that the 8×10 market would be big enough to support the project. It failed as well. What we learned from building the prototype, other than it was a quick way to spend a whole bunch of money, was that the SP-445 design just doesn’t scale very well.

One example: as the tank gets bigger, the amount of liquid required grows quickly. The prototype SP-2810 required almost two litres of chemistry. Not only did we have problems with the lid sealing watertight, but it was also extremely awkward to handle. Agitating the chemistry turned into quite a workout! It was also awkward to load. On the production side, the mold costs were blowing past the budget constraints. For example, the mold for the SP-445 tank weighs in at just under 500 lbs; the mold for the SP-2810 tank would have weighed around 3000 lbs. We knew we had to rethink the solution.

EM: You had a blog post about a “taco” tank a while back, didn’t you? What happened to it?

Tim: Yes, the SP-1810T. It had the cross-section like a giant teardrop and actually worked pretty well. Its demise wasn’t just one issue but, like in many product development projects, what I call the three “M”s killed it: the market, the method and the money. They seemed to conspire against it.

EM: Let’s take those one at a time, starting with the money.

Tim: Well, as I’ve said before, every engineering decision comes down to economics. In this case, the long, narrow mold with a complicated insert was getting expensive. Both the tooling cost estimates and the production estimates were getting out of hand.

As for the method, that’s the “how” or the technical challenges that you run into. The design was getting complex and getting the lid to seal it was tricky. There were issues with loading and unloading without scratching the film. As for the market, the design could only handle 8×10 film. That eliminated the 5×7 market, which is probably about 25% of users. Of course, that directly impacts the money side of the equation. After playing around with it, we knew we had to find a better answer. After researching the topic, talking with large format gurus and, really deleting a bunch of files and starting with a blank screen, we ended up revisiting the tray concept.

EM: What did revisiting the tray concept involve and how did you arrive at the single sheet design?

Tim: We had thought about it before but didn’t like the overly complex film holders we thought we’d need — which is why we tried the SP-1810T. Then, after getting back on the tray concept, we got fixated on processing two sheets of 8×10 at the same time. After several months of getting it to almost work, we decided to ask our customers what they really wanted.


Most of them told us that a single sheet was enough. If I remember right, only about 15% said that processing two sheets at once was a firm requirement. In fact, almost 20% said they’d never process more than one sheet at a time anyway. The rest said that a two-sheet option would be nice but not that important.

EM: 8×10 photographers aren’t exactly high-volume shooters…

Tim: Exactly! And a lot of 8×10 shooters will process one sheet normally and the next as, for example, maybe N+1, etc. By dropping the two sheet requirement, we had all kinds of options open up. Mainly, we were able to simplify the film holders and eventually, realized we really didn’t need one at all.

EM: So no film holders, you just drop the film into the tray? Just how does that work and what impact does it have on the anti-halation dye on the rear side of the film? Are you limited to just 8×10 film?

Tim: Several physical characteristics work together to make this work: first, film is heavier than water. It has a density of around 1.5 g/cm3. Water, by definition, has a density of 1g/cm3. So film wants to sink. Also, wet film is flat. The third trick we’re using is the surface tension between the film and the tray. Presoaking the film, ensures that it’s flat and stuck to the bottom of the tray, so when you add developer, the liquid flows across the film and the film stays below the surface.

If the film is stuck to the tray, you might wonder how the anti-halation (on the underside of the film) is removed. The surface tension is only present when the tray is empty, since there’s no surface tension underwater. This is why you can walk on wet sand along the beach without sinking in but you sink into the sand as soon as you step into the water. So once you fill the tray, the film is free to move about.

For insurance, we added tabs on the lid to hold the film down, just in case you get too wild when agitating. Frankly, I don’t usually use them with 8×10. The design only requires the use of 500ml of chemistry, which was one of the attractive features of a horizontal design vs a vertical design like the SP-445. In fact, you can get by with much less. Some users have reported using only 200ml for a sheet of 8×10; I think that’s pushing the limits. I usually use around 350ml.

The device also allows the development of multiple sheets of 5×7 and 4×5 sheet film, as well as glass dry plates from Jason Lane. (EM: I should also thank Jason for some of the photos you see in this article.)

EM: You now have the 4th iteration of the SP-445 and the SP-8×10. What’s next for Stearman? Are we talking iteration of what you already have or can we expect development tools for smaller formats?

Tim: The small format world is pretty well equipped! We are going to stay focused on large format and related accessories. We’re prototyping the ultimate tripod and researching a film developer optimized for sheet film. Nothing we can share yet; hopefully, we’ll have news later in summer/fall 2020.

We also plan to produce more “Intro to Large Format” videos. Of course, we’re open to suggestions, so if any of your readers have ideas they would like us to cover, we’d love to hear them.



Garden shed tinkerers and small manufacturers about in the film photography community and along with Mod54, Chroma Cameras, ars-imago and others, Tim and Stearman are working to provide options that are either too niche, or have gone ignored by larger companies chasing the dragon of high volume sales.

I appreciate being given the opportunity by Tim to pull back the curtain, as it were and welcome you to pose all and any questions to him here in the comments below.

~ EM

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