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Rescue a ratty Rietzschel, deep cleaning the Kosmo Clack
Kosmo CLack stereo camera

Acquired in early 2023, this Rietzschel Kosmo Clack looked passable from a casual look over, even if the shutter was completely dead, making it cheap. The lenses were filthy and it was generally neglected but mostly there with just one dress screw missing, no case or plate carriers. The focus screen was there and unbroken, so we took a chance. It sat in the spares bin/job list until I took it upon myself to see if I could locate some plate carriers for it. Having acquired a handful, the Rietzschel was bumped to the head of the queue. I didn't intend to do a project page for the Kosmo Clack so the process hasn't been completely documented, but what initially started out as a fairly regular deep clean 'morphed into a much greater endeavour, but illustrates well the approach of repair, restoration and conservation I employ.

This is as it arrived, looks pretty good cosmetically with an appropriate level of patina from a camera that seems to have been used a fair bit. Obvious issues to repair are, shutter showing no signs of working, septum not working, spirit levels evaporated and all functions very stiff bordering on seized.

Compur Stereo shutter The Dial set Compur Stereo shutters are attached to a brass plate that can be released first by swinging a nickel plated lever to the vertical then pressing upwards against a resistive spring to allow the bottom to release first then the top edge. There's no need to remove the shutters from this plate unless you want to take the mechanisms out of the case, but doing so entails removing eight screws tapped into the mounting rings. You will lose the focus relationships by doing this, so a couple of scratch indications are required for later, or set up freshly, which is my preference anyway. All the dials were taken off and the design is well thought out, being difficult to put back incorrectly, providing you have taken care. The speed setting and escapement cams are mounted under the speed dial, just make a note of their orientation when removing, they can only go back in one way correctly. This photo was snapped quickly just to make a quick record of which screw came from each hole as there are short, medium and long screws. The etched markings are dirty and dull but the paint is in good order with some light brassing. It will be cleaned but otherwise left as it is.
Compur Stereo shutter with faceplate removed There are contemporary documents from 1916 showing the Kosmo Clack fitted with Compound shutters, but the illustrations are drawings not photographs, I've yet to see one with a Compound. The Dial set Compur arrived in 1912 and the Stereo version likely later, the date universally attributed to the first Kosmo Clack is 1914. Anyway here is the Stereo Compur with the face plate removed. It's a bit grubby, but no obvious signs for seizure, nothing appears to be out of place, but it resisted any attempts to move the shutter leaves. On the left is the master shutter with the slave on the right. The slave shutter is just a standard dial set Compur with all the machining and even drillings completed, but they stopped short of actually tapping the drilled holes. The brass posts for the shutter lever and speed dial can be swapped over as unworn spares for the master. Both on the master side were showing a fair bit of wear and were loose and wobbly. Across the middle is a saddle that pins the shutter assemblies in place, both screws have their heads torn by an oversize screwdriver, the first indication that someone has been in here for a fiddle in the past. The long bar along the bottom transmits the drive from the master shutter to the leaves of the slave. Each side has a return spring but the opening is powered solely by the master. The cast zinc case is almost black with oxidation, it would have been bright silver a century ago.
Compur Stereo shutter master mechanism

The oxidation was so strong it had bound the mechanisms to the case, requiring considerable pressure to release them. But once out the master side was happy to show signs of working, although far from happy. The slave side was locked solid. This is the back of the master, just before removing the shutter leaves for a polish and clean, this photo was to record the stacking order, the leaves themselves are identical. This isn't true of the slave, one leaf has a notch cut out of it to clear a protruding screw head.

Mostly it looked fine, there was some rust coating some of the timing brake gears, a fair bit of dust and dried grease. The slave side shutter leaves were locked together with rust and the driving ring was over tight, a clear witness mark showing binding. A good clean of everything had it all moving satisfactorily. Whilst the leaves are blued spring steel, they also have a thin layer of paint on them, it looks contemporary.

Compur Stereo shutter, apertures The aperture setting was very stiff and unpleasant to move, so all the leaves came out, twenty leaves and forty pins to align later, much fun to be had. As every leaf needed cleaning and polishing, the trick of removing them at f/22 as a single meshed lump wasn't going to happen. All the leaves were placed in two sets to keep them together, de oxidized so the brass pins were bright and smooth, then polished so they run over one another smoothly. The heavily blackened case was also de oxidized and then re painted as there were obnoxious scratches around the edges. I set to putting the leaves back in using my 45mm ten leaf Compur jig I created a few years ago but struggled to get it to align. I think it was on the seventh attempt when it occurred to my dim witted self that I should check the diameter between the rear pins. My jig is for a later rim set Compur... this earlier Dial set turns out to be 1mm narrower. After making a new jig it went together rather more easily. Like the shutter itself, the drive between master and slave sides is transmitted via the bar at the bottom. This shows it all back together, the case now bright but with a few etched pits. It will dull over time as zinc does naturally. But now it all moves easily as it once did.
Compur Stereo shutter, master side cleaned This is the master side post cleaning, but before the leaves are refitted. Dismantling was initially kept to a minimum. These days I use a rather unorthodox but agreeably effective method of cleaning these shutters. Automotive aerosol clutch and brake cleaner, blasts a jet of low flash point solvent in prodigious quantities that sends dust, dried grease and general poo running for the hills. It evaporates completely with no trace of a film remaining. A sable paint brush can be used to move things around in the fluid before it evaporates then a back up squirt clears most of it away. I then follow up using an eye loupe and polish with a highly sharpened cocktail stick to each gear tooth. The timing brake escapement mechanism wasn't rocking properly and needed several jets before it freed up and there was rust under the saddle that holds down the timing gears. It all seemed much happier after that and was all put back.
Compur Stereo shutter, master and slave Both shutters cleaned with the master about to get the three polished shutter leaves returned to their rightful position. With the oxide removed from the casing the mechanisms snugly sit into their recesses tightly enough not to fall out. The slave goes in first, so that the actuating lever can slip over the pin without stressing it. The accuracy of the parts is spectacular, any error results in the slave opening early or late, resulting in different exposures on that side. A problem more pronounced at smaller aperture settings. There is a tiny amount of adjustment that can be made by tightening or backing off the kink in the lever, but the amount required is miniscule for a fairly large result at the leaves. There is sufficient wear in this shutter for there to be some discrepancy, but it varies slightly between each release so has to be tolerated as it it. It amounts to an error of about a quarter stop at f/22 and negligible at full aperture. Jules Richards avoided this shortcoming on their Verascope by using a guillotine shutter.
Compur Stereo shutter

The lenses looked pretty bad and the muck was baked solid, as though sat in a window for a long time. There were some fungal spores sending their telltale trails on the inside faces of all elements but the usual acetic bath saw those off and the glass ended up coming out brighter than I first expected. There are relatively few scratches and not etching, but there is an annoyingly large bubble inside f/11 in the rear element of one lens. Bubbles in the glass of even high quality lenses was not uncommon in this period.

This shows the casing with all the makers marks cleaned up and bright once more. The number on the left side is not the serial number of the lens but the general model number of the shutter, the serial number is lightly stamped into the bottom of the shell and is easily missed.

Rietzschel Kosmo Clack, focus rack end

Turning attention to the main body this picture illustrates the general theme, nothing disastrous, just a bit tired. The level has evaporated, there is general pitting to the vitreous enamel on the side bracket, the leather has been peeled back in the past a few times and stuck back and the engraved markings on the focus scale have lost their in fills. The pale yellow scale is a very early man made material known as celluloid widely used to replace bone at this time. It's manufacture had been perfected in the late 1800s and was also used in clear form as the base material for the early roll films. The scale is slotted to allow some adjustment after the lens and focal plane have been set up at infinity, arranged when the camera is fully closed, so that it cannot focus through infinity.

The main issue with the camera now was peeling internal paint and the non functioning septum. Cleaning back the paint would result in a lot of dust, potentially getting into the weave of the bellows liner, for this reason the entire camera would need to be stripped of every part to remove the bellows and septum.


Celluloid focus scale This innocuous looking scale is similar to many found on cameras, but the material is interesting being regarded as the first plastic. It's origin dates back to a 1862 patented material known as Parkesine, the basis of which is the residue remaining from evaporated Collodion, used in early photographic emulsions prior to gelatin. Collodion itself was a derivative of nitrocellulose which gives these materials their family name of celluloids, ranging in solid Ivory replacements to thin films used for early photographic film bases.
Kosmo Clack, septum removed The bellows had to be removed both to protect them from the cleaning process and also allow the septum crutches to be removed, as the screws for these are hidden under the final glued down bellows pleat. Originally the bellows were attached with shellac. At some point in the cameras existence they had been removed twice, being subsequently glued back in with some hard glue then industrial double sided tape. This left the final pleats at either end very stiff, irregular and sticky. The septum itself is sprung into place locking two pivots into the crutches. This image was taken just for a visual note of the arrangement prior to taking it all apart. The construction broadly mimics a shutter curtain with a spring roller one end, around which is wound sealed shutter curtain cloth and the leading edge riveted through. The curtain material had rotted and broken down, being stiff, cracked and full of holes. The pin holes aren't quite as critical in this usage as the light is passing by very acutely and unlikely to pass through, but the curtain was going to be replaced as it was way too stiff and beginning to tear.
Kosmo Clack, septum curtain, rotten The original septum curtain removed. The entire assembly is a little tricky as the anchoring of the spring roller entails soldering the ends in place. The rivets in the end plate were driven out, reformed and reused, but a bead of cyanoacrylate was used to make absolutely sure it didn't spring apart.
Kosmo Clack, septum restored It's crucial to get the hanger on the left adjusted correctly, and it's a surprisingly frustrating task. Clearance internally is barely 0.75mm top and bottom. It must swing straight, or will contact the inner faces causing it to stick. It needs to stop perfectly vertical whilst bisecting the plate precisely and swing smoothly to one side to allow uninterrupted wide angle images to be made. The filed notch filed allows it to clear a small screw head that serves as a pivot to push the leading edge over to centre in the final few degrees of travel. In terms of restoration, the functionality was repaired, but patina conserved. This shows the septum with the new curtain, the hanger repainted but the remaining signs of age retained.
Kosmo Clack,  castings The Kosmo Clack's main components are two zinc castings. Shown here are cleaning and repainting the matt black inner faces. Much of this paint was scraped off in the past but sufficient traces remained where it had once been. The paint used is again unorthodox, my choice being Pot Black, a high temperature engine cylinder paint that has good adhesion with alloys and can be oven baked to harden it. The original paint seems to have been applied by hand so this approach was made too. It dries to a very period looking finish and is indistinguishable from the original, had I not 'fessed up, you'd never know. In this form the septum was put back in, taken out, tweaked then put back in many times before I was happy with it. It's easier to do this process before cementing the bellows back in. The bellows themselves were given a real birthday party, being parallel they were relatively easy to do. First straightened out gently then damp washed allowing the card stiffeners to become damp. Then dried flat to remove a crease as far as possible. Then a leather feed followed by neats foot oil, after that Venetian cream stain and finally antique wax. The wax is useful to prevent the pleats sticking together if the cement oozes out during the final sticking back in process. After all this the rear most and front pleats were still a little stiff and irregular and with no pressure plate to hold them flat it seemed likely light would creep in at these points. Ordinarily I use PVA to glue bellows back in, as it can be undone later if needed. However it tends to dry clear. I have another concoction that can be used as a cement, consisting of PVA mixed with black drawing ink. The two mix reacting chemically to produce a paste thicker than either, dries opaque and has decent filling properties, it dries in 24hours. The rear face was glued in first, the front only being attached once the the rest of the camera was finished. The focus pinion shaft needs to go back in prior to cementing the bellows into the main shell.
Kosmo Clack, focus lock The original leather covering was not retained. The embossed pattern had relaxed significantly and it had been peeled back and glued down a few times previously. It had to come off completely to remove the pinion shaft as it's retained by two brass inserts hidden beneath the lower covering. The leather was soaked off which didn't do it any favours, but I'd already elected to replace it as I had a perfect match amongst my goat skins, both in texture and thickness. this detail image shows one corner after the new covering was attached but also shows the focus lock screw. This screw has a blade filed into the protruding end that locates between the pinion teeth locking the focus as desired. The blade end is aligned with the screw slot so you know how it's orientated, it remains accessible at all times and is set at an angle to clear the lens board allowing it to be adjusted. Don't turn the screw with the pinion pushed in, you'll bend the blade and damage the pinion teeth.
Kosmo CLack stereo camera, pre restoration Kosmo CLack stereo camera post restoration

This is a more subtle restoration than some of those covered in the project pages. Sat in the display case you'd not be aware much has been done to it. All the light brassing is retained but everything now functions smoothly, easily and as it ought to.

The plate carriers need some rust treatment and a good clean before some cut film can go in, but it's on the way there.

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