Restoring Stereoscopic Antiques

written for the stereosite by Pascal Martiné, Germany

Why Restore? Guiding Principles

A lover of antiques also loves the sto­ries they come with and the traces those sto­ries have left – some­thing which we call ‘pati­na’. We must thus ask the ques­tion of why one would even con­sid­er restora­tion, a process which will sure­ly alter an object.

Water stains, cracks, even the loss of parts — are these flaws wor­thy of restora­tion? Don’t we have to pre­serve the arti­fact as it is, with its his­to­ry intact? This is cer­tain­ly a valid are­na for debate. For me per­son­al­ly, there are some very good argu­ments for restora­tion. How­ev­er, one should always err on the side of cau­tion. These are applic­a­ble to antiques in gen­er­al, but are par­tic­u­lar­ly rel­e­vant when con­sid­er­ing stereo­scop­ic antiques:

First­ly, it is usu­al­ly a goal of mine to restore the func­tion­al­i­ty of stere­o­scopes and stereo cam­eras to a point where they are still usable as intend­ed. This also includes con­ser­va­tion, ensur­ing that func­tion­al­i­ty will not be lost in the com­ing decades.

Sec­ond­ly, things like dirt or water dam­age might pre­vent us from under­stand­ing how an object may have looked orig­i­nal­ly, or how com­fort­able it may have been to use; in short, how the object would have appeared to its con­tem­po­raries. This, in my opin­ion, is also part of his­tor­i­cal research on a par­tic­u­lar object.

Inevitably, antiques are only ever avail­able in lim­it­ed quan­ti­ties. Their cur­rent own­ers might not always con­sid­er them to be worth pre­serv­ing, although the Inter­net now makes it easy to get back­ground infor­ma­tion and esti­mate the demand for objects. Nev­er­the­less, a stere­o­scope or stereo cam­era that is in poor con­di­tion is less like­ly to find a buy­er, and might there­fore per­ma­nent­ly dis­ap­pear. In addi­tion to a mea­sure­able increase in val­ue, a restora­tion is often the last resort in sav­ing an object that has already sur­vived destruc­tion for a cen­tu­ry or more.

I have already men­tioned that the pati­na of an antique is a con­sid­er­able attrac­tion, and it is desir­able in any case that the age of an antique remains obvi­ous to the observ­er. When I restore a stere­o­scope or stereo cam­era, I am not try­ing to give the impres­sion that it is a mod­ern prod­uct. It is also not my intent to improve its per­for­mance from how it was orig­i­nal­ly con­struct­ed, even if lat­er mod­els from the same man­u­fac­tur­er did exact­ly that.

When con­sid­er­ing restora­tion, I always ask myself one very sim­ple ques­tion: What would this stere­o­scope look like today if it had nev­er dis­ap­peared from its own­er’s liv­ing room, but had been cher­ished and cared for con­tin­u­ous­ly for over 100 years?

Disassembly and Reassembly

Look­ing at an old stere­o­scope, it is easy to see that the mov­ing parts are worn, and that freely acces­si­ble sur­faces show abra­sion. This is usu­al­ly the result of nor­mal use and super­fi­cial clean­ing. Stub­born dirt is main­ly found in cor­ners and cracks, or behind levers, cranks, knobs, or the ocu­lars. Nor­mal use main­ly leaves behind dust and bod­i­ly flu­ids, such as sweat, which has hard­ened from decades of stor­age in damp and poor­ly ven­ti­lat­ed rooms.

Whether you want to per­form a rel­a­tive­ly super­fi­cial clean­ing or a full restora­tion, it is impor­tant to dis­as­sem­ble the stere­o­scope as much as pos­si­ble! There are four main rea­sons for this:

First, there are some areas that you sim­ply can­not reach at all, e.g., the inside of the open­ings through which the eye­pieces are moved when focus­ing. But it is pre­cise­ly in these places that fur­ther abra­sion tends to hap­pen when the stere­o­scope is in use.

Sec­ond, dif­fer­ent mate­ri­als require dif­fer­ent clean­ing tech­niques. Clean­ing wood with liq­uids dam­ages met­al parts and, con­verse­ly, pol­ish­ing met­al makes neigh­bour­ing shel­lacked wood parts look dull and scratched. With­out com­plete­ly dis­as­sem­bling an object, there is no way of com­plete­ly clean­ing the areas of tran­si­tion from one mate­r­i­al to the other.

Third, clean­ing some­times requires the appli­ca­tion of some mechan­i­cal force to the object. Not to men­tion clamp­ing parts that need to be re-glued, using a ham­mer to fit in miss­ing parts, or replac­ing lost nails. If every­thing is still assem­bled, you may loosen, bend, or break intact con­nec­tions in doing so.

Final­ly, this is also about the phi­los­o­phy of restora­tion. We want to work con­ser­v­a­tive­ly through­out the entire process and, if pos­si­ble, even reverse process­es of decay. How­ev­er, if you were to clean an object with­out dis­man­tling it first, you may actu­al­ly accel­er­ate the process of decay. This is because wear will inevitably con­tin­ue on the freely acces­si­ble areas by your clean­ing activ­i­ty, while dirt in cracks and crevices has not ever been reached. This might lead to a sit­u­a­tion where you have to apply new paint because you rubbed the worn old paint off the already worn wood­en sur­face even though you real­ly only want­ed to get to the back of a Bake­lite knob.

Tools

A small stan­dard tool­box is ide­al for dis­man­tling, since it usu­al­ly con­tains screw­drivers in var­i­ous sizes as well as flat-nose pli­ers and side cutters.

If you want to fix, grip or pull some­thing with the flat-nose pli­ers, remem­ber to use a piece of fab­ric or cork to pre­vent the pli­ers from scratch­ing your sur­face. You can use the side cut­ter to loosen (not to cut off!) small nails. This is espe­cial­ly use­ful for remov­ing things like manufacturer’s labels.

The most impor­tant tool, how­ev­er, is the screw­driv­er. Stereo­scop­ic antiques typ­i­cal­ly uti­lize slot­ted screws exclu­sive­ly (not Phillps head or Allen head). For the small­er screws, you may have to resort to watch­mak­er’s tool sets, but stan­dard screw­drivers can usu­al­ly be used suc­cess­ful­ly here. How­ev­er, espe­cial­ly the larg­er screws used in antique stere­o­scopes tend to have much nar­row­er slots than mod­ern screws of the same size. So, a mod­ern screw­driv­er of the prop­er blade width won’t fit in the slot, while a watchmaker’s screw­driv­er which is thin enough to go in the screw slot won’t be wide enough to apply the mechan­i­cal force nec­es­sary to turn the screw. My rec­om­men­da­tion: Buy a large screw­driv­er with a com­fort­able han­dle and a blade about 4 mm (i.e. 1/8 in) wide and grind the blade down to be much thin­ner — as flat as a but­ter knife.

If with the right tools, many screws will still refuse to loosen straight away. If the shanks are met­al, care­ful­ly spray the head with some pen­e­trat­ing oil, e.g. spray-on WD-40, and leave it to do its job. Some­times you will have to do this mul­ti­ple times before unscrew­ing is possible.

If the screw head is recessed deep into the wood, it helps to care­ful­ly scrape the head free with a knife.

If the screws are dirty, you can scrape out the slot in the screw with the cor­ner of the screw­driv­er head. It might also help to loosen the screw by try­ing to turn it back and forth a lit­tle at first. If it gets dif­fi­cult and you have to use more force, hold the neck of the screw­driv­er to keep it from slip­ping and scratch­ing the surface.

Procedure

I have come across dif­fer­ent makes and mod­els of stereo­scop­ic antiques time and again over the past few years and it is impos­si­ble to give a com­plete expla­na­tion. Still, there are a few things in common.

For exam­ple, eye­pieces or lens­es can usu­al­ly be unscrewed and dis­as­sem­bled by hand. Beware of too much pres­sure! If you grip them too tight­ly, you may break or bend the eye­piece mounts or the thread­ed rings! It’s best to place your palm flat against the entire ring and then twist. If your hand keeps slip­ping, try putting on rub­ber gloves.

Levers that do not have a screw can some­times be amaz­ing­ly easy to pull out. Often, how­ev­er, nipped nails also serve as pins for hold­ing them in place. If this is the case, these levers are gen­er­al­ly impos­si­ble to detach.

If pris­mat­ic lens­es or glass panes are held in place with pieces of wood glued inside the device, see if you can gen­tly break off these pieces of wood with your bare hands. You can also use a knife or a screw­driv­er as a lever. Make sure that any dam­age you may cause will not be vis­i­ble from the out­side and con­sid­er whether it is worth dis­man­tling this part of your object for the restoration.

Depend­ing on the order in which you do things, you won’t have to dis­man­tle every­thing at once. For exam­ple, it is advis­able to keep eye­pieces assem­bled when you are not work­ing on them so that you don’t have too many small parts out at a time. A type case or a mag­net­ic tray is ide­al for stor­ing the small­est parts.

The mech­a­nisms inside larg­er table stere­o­scopes can usu­al­ly be tak­en out of their cas­ings and cleaned with­out fur­ther dis­man­tling is necessary.

When reassem­bling the device after clean­ing, you will notice that screws or nails may no longer grip because the hole has got­ten too large. To fix this, spread some wood glue on the tip of a tooth­pick, insert it into the hole in the wood, and then break it off. To pre­vent the screw from chang­ing its posi­tion, you can use a small nail to pre­pare a hole in the screw’s orig­i­nal posi­tion by hand.

Expect hav­ing to replace rusty screws and not be able to reuse small nails. It’s impor­tant to check your local hard­ware store for suit­able replace­ments before dismantling.

Cleaning and Finishing

The major­i­ty of my restora­tion process con­sists of very thor­ough cleaning.

Lacquered Surfaces with Glossy Finish and Bakelite

I use the same clean­ing flu­id for shel­lac-pol­ished wood, lac­quered met­al with a glossy fin­ish, and Bake­lite parts. There used to be a prod­uct from the Ger­man com­pa­ny Clou for pol­ish­ing shel­lac – a water-based sus­pen­sion that con­tained a lit­tle soap and pumice pow­der as an abra­sive. The liq­uid soap was ide­al for loos­en­ing encrust­ed dirt, and the abra­sives smoothed the sur­face with­out leav­ing any vis­i­ble marks. The flu­id was applied with a ball of cloth and, after dry­ing, pol­ished with a clean cloth until it was shiny. Unfor­tu­nate­ly, this prod­uct was discontinued.

Two years ago, I final­ly came across an alter­na­tive that is easy to make at home. There are many dif­fer­ent pol­ish­ing pastes for car paint that con­tain abra­sives. Look for a water-based prod­uct and above all, make sure it does not con­tain any wax or sil­i­cone. Dilute the prod­uct with water until it has reached the con­sis­ten­cy of milk.

The appli­ca­tion is then exact­ly as described above – there will prob­a­bly be some light cloud­ing on the sur­face after the prod­uct has dried (like­ly due to the abra­sive), but it can eas­i­ly be wiped off with a damp cloth. After­wards, you should dry the sur­face quick­ly with a fresh, clean cloth and pol­ish it until it is shiny.

A final treat­ment is option­al after clean­ing. Bake­lite gets a nice, even shine if you treat it with colour­less wax. Usu­al­ly there are spe­cif­ic prod­ucts for the care of antique wood­en fur­ni­ture. After rub­bing the wax in, let it dry com­plete­ly and pol­ish it briefly, and thor­ough­ly, with a dry cloth until it shines.

The same treat­ment is also use­ful for wood with a shel­lac sur­face; iso­lat­ed scratch­es or blunt spots can be con­cealed well this way. How­ev­er, be care­ful to apply very lit­tle wax and avoid unnec­es­sary con­tact with the sur­face for sev­er­al days after pol­ish­ing. The wax takes a long time to dry com­plete­ly because it can­not be absorbed into the wood. Don’t wor­ry about over­do­ing it. You can com­plete­ly remove excess wax with a soft cloth. I strong­ly advise against treat­ment with stan­dard liq­uid oily stan­dard fur­ni­ture pol­ish! The oil pen­e­trates even the small­est cracks in the paint and pulls into the wood under­neath. This results in dark spots, that will be irre­versible or at least vis­i­ble for a long time.

Cau­tion: Repairs to wood, met­al and Bake­lite parts must be made before the final treat­ment of the surface!

Waxed Wood

I gen­er­al­ly try to change the orig­i­nal sur­face as lit­tle as pos­si­ble. An excep­tion is waxed wood, as there are water stains under the wax lay­er and new wax that is applied to the sur­face com­bines seam­less­ly with exist­ing wax residues (in con­trast to lacquer).

If the dirt is just super­fi­cial, I resort to the same method I explained in the pre­vi­ous sec­tion. In the case of water stains, heav­i­ly bleached wood, or par­tial loss of the wax lay­er, I remove the old wax lay­er or loosen it. To do this, I rub the wood thor­ough­ly with a bale of the finest steel wool (grade 0000), which I reg­u­lar­ly soak in clean­ing gaso­line. This process wash­es off the old wax and at the same time smooths the sur­face. The result always looks ter­ri­fy­ing. Sur­faces appear spot­ty and extreme­ly cloud­ed, like a bad­ly wiped school blackboard.

Do not try to repeat the process until the wood looks even, as this would mean that you’ve sand­ed off the entire top lay­er of the wood. This is nei­ther desired nor nec­es­sary, and would only dis­tort the orig­i­nal colour. You can always check how the sur­face will look lat­er as long as the clean­ing gaso­line has not evap­o­rat­ed and the wood is still damp.

From here there are sev­er­al options:

a) Deep scratch­es, break­outs, or oth­er areas where the orig­i­nal sur­face has been com­plete­ly removed and which there­fore emerged bright­ly before remov­ing the wax lay­er can be re-coloured with wood stain (water-based with­out any wax com­po­nents) in the appro­pri­ate colour.

b) If the wood in gen­er­al, or in larg­er areas, looked very pale and colour­less, you can rub the entire wood with lin­seed oil var­nish. Let the var­nish take effect briefly, rub off any excess liq­uid with a cloth and let it dry sufficiently!

c) If, by and large, the wood looked even and had a nice colour before remov­ing the lay­er of wax, skip both of the above steps and apply a new lay­er of wax straight­away. Use a colour­less wax made for wood­en fur­ni­ture. There are often spe­cial prod­ucts for antiques. Dis­trib­ute the wax with a piece of cloth. Too much wax won’t harm your sur­face, but it will cause you to have to pol­ish more. For starters, the sur­face should feel like your hands after putting on hand cream. Let the wax dry long enough and rub it off briefly and vig­or­ous­ly, cre­at­ing a satin gloss. Rub­bing for too long will heat up the wax, caus­ing you to mere­ly smear it around. If in doubt, let it dry again. Cracks and ridges are eas­i­ly pol­ished with a brush. If at the end you still see rub­bing pat­terns, you have prob­a­bly used too lit­tle wax, or the wood has soaked up too much of it. In this case, just repeat the process.

Cau­tion: repairs to the wood must be made before oil and wax are applied!

Metal

Clean­ing met­al parts that have not been paint­ed or tem­pered is gen­er­al­ly very easy, but might require patience and focus. For stereo­scop­ic antiques, you’ll most­ly encounter brass, and pos­si­bly nick­el-plat­ed brass. Rub off any dirt or stains with the finest steel wool (grade 0000) with­out apply­ing too much pres­sure. Not all stains can be com­plete­ly removed, and you always have to con­sid­er when to stop. There are lim­its to clean­ing, espe­cial­ly with nick­el-plat­ed brass.

Tem­pered met­al can some­times be cleaned at least a lit­tle with pen­e­trat­ing oil and a cloth. But be very care­ful: even a lit­tle too much pres­sure will cause the colour to come off.

The clean­ing of the mechan­i­cal work of table stereo view­ers is most­ly done by sim­ply remov­ing dust, dried-on oil, or graphite. I use a tooth­brush on which I put pen­e­trat­ing oil, for exam­ple spray-on WD-40. I rub larg­er areas clean with an oil-soaked cloth. Oil the mov­ing parts, but oth­er­wise rub off all of the oil after­wards. Do not use sand­pa­per or steel wool. Unfor­tu­nate­ly, I speak from expe­ri­ence when I say that these leave per­ma­nent traces.

Leather

I use Vase­line or mod­ern coloured shoe pol­ish to care for leather. I make sure not to use any prod­ucts with grease, as it tends to react with the leather in the long term, mak­ing it brit­tle. Fur­ther infor­ma­tion can be found with­in the book restora­tion com­mu­ni­ty if needed.

Repairing and replacing

In com­par­i­son to pos­si­ble seri­ous dam­age, every­thing that has been said so far is rel­a­tive­ly man­age­able. If a stere­o­scope or stereo cam­era is not only heav­i­ly soiled, but has parts that are bro­ken off, per­ma­nent­ly stuck togeth­er or have even dis­ap­peared com­plete­ly, you must always decide on a case-by-case basis. Still, there are a few com­mon meth­ods that I would like to address briefly:

Gluing

Bone glue was most fre­quent­ly used in antiques, and we can­not pro­duce it today with­out great effort. That is why I myself use mod­ern glue for my restora­tions. I make sure, how­ev­er, that it doesn’t con­tain any sol­vents, because I don’t know to what extent those sol­vents might attack the materials.

Usu­al­ly wood glue takes some time to dry, mak­ing it is essen­tial to hold the parts togeth­er with clamps. Don’t for­get to put wood or card­board under­neath the clamps to avoid scratch­ing the sur­face. I also use white book­bind­ing glue for leather or tex­tile. Book­bind­ing glue retains some elas­tic­i­ty and dries clear.

White glue that spills out from cracks when glu­ing things can be eas­i­ly scraped off with a fin­ger­nail once it has hard­ened a bit. Any left­overs can then be wiped off with a damp paper towel.

Super­glue is use­ful for bro­ken Bake­lite parts and two-part resin epoxy is suit­able for met­al parts that are sub­ject to stress.

Bending

Bent met­al parts are very com­mon. Most­ly they are not cast met­al parts, but rather wires, stamped sheet met­al or the like. If you are care­ful and think care­ful­ly about where to start, most parts can eas­i­ly be bent back into shape. I most­ly use flat-nose pli­ers for this. Don’t for­get to put a piece of fab­ric between the pli­ers and the met­al part! I usu­al­ly only use only one pair of pli­ers while I hold the part with my bare hand. I like to think that that gives me a bet­ter sense of how much strain the met­al is under when bending.

Coloured Wax Putty

It is not uncom­mon for antiques to be infest­ed with house­hold pests, e.g. wood­worm. After dis­man­tling, it makes sense to treat the infest­ed parts either with a pes­ti­cide, or put in the oven. The tell-tale holes in the wood can usu­al­ly be hid­den well with coloured wax. Coloured wax is also good for fill­ing in small cracks or imper­fec­tions, both in wood and in Bakelite.

Felt

Even after a num­ber of restored stere­o­scopes, you can still dis­cov­er new things! Many stere­o­scopes have two met­al rings in their wood­en cas­ings, through which the tubes of the eye­pieces move when we adjust the focus. Felt or vel­vet was always used inside these rings. How­ev­er, one can often no longer find the slight­est trace of it. If you look close­ly, you might at least see the glue residue. I def­i­nite­ly rec­om­mend putting a thin lay­er of felt back on. This pre­vents the met­al tubes from being scratched and, above all, sta­bi­lizes the guide when set­ting the focus, which often remains a bit wob­bly with­out felt.

Spare Parts

Although I said at the out­set that restora­tion is some­times the last chance to save an antique from destruc­tion, there are also those that are too dam­aged to save. Keep an eye out for these objects. Some­times they can serve as a source of replace­ment parts. In par­tic­u­lar, the eye­piece frames and Bake­lite parts were made by large man­u­fac­tur­ers, and are the same for most stere­o­scopes. The same thing is true for screws. Even if you ever need to replace a piece of wood, it is cer­tain­ly prefer­able to use a vin­tage piece of wood that might allow you to keep the orig­i­nal shel­lac surface.

Conclusion

I would like to return to my guid­ing ques­tion: “What would this stere­o­scope look like today?” Restor­ing always brings me clos­er to a pos­si­ble answer even though this remains always just an approx­i­ma­tion. Anoth­er pic­ture that I used in my arti­cle was to reverse a process of decay. This means, restora­tion is always like a jour­ney into the past and even if you restore reg­u­lar­ly, you will nev­er know where it leads you. Anoth­er aspect is becom­ing kind of inti­mate­ly famil­iar with the object you are work­ing on, exam­in­ing it close­ly, decid­ing wether to do a step of restora­tion or not and still being excit­ed. Turn­ing an old and for­got­ten stere­o­scope into a tru­ly per­son­al object is invalu­able. It’s more than just find­ing it. In some way it’s also recre­at­ing it and lit­er­al­ly becom­ing involved in its history.