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General Information installing and removing light seals in film cameras. revised June 3rd 2016

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Organize before you start.

Locate a clean ,ventilated work area that is well lit.

Tool List

A small amount Naphtha, mineral spirits or your favorite solvent that is plastic friendly.
A pair of technicians quality curved or straight  tweezers
Dental pick
Exacto knife
Kimwipes (or paper towels)
Rubbing Alcohol
Technicians work mat
Toothbrush
Toothpicks (both square and round)
Q-tips with paper sticks

Adhesive Delay agent:

Hand Sanitizing Gel 70% Alcohol (additive free)
Rubbing alcohol
Water ( recommended)

Handling the smaller foam pieces is easiest with a pair of tweezers.

Preparing for removal.

You never need to hurry. 

The most important and time consuming work is removing the old seals. Focus on clean, clean clean. Clean the old residue from the door channels, mirror cushion area,  door hinge area and anywhere else you are replacing the seals. The finest adhesive in the world will not adhere to that sticky, gooey residue that was once a quality light seal. Proper installation will give you thousands of light tight exposures.

Removing Old Seals

Put some of your solvent (1oz) in a small container.

The easiest way to apply the solvent is to take tweezers and put the points into the solvent. Then squeeze the points together, then relax them a little and withdraw the tweezers.  Capillary action should have the solvent in between the points.  Look carefully at the tweezers points while they are in the solvent. You will notice the distance between the tweezers points  (as you squeeze and release them) dictates how much solvent they will hold. Practice a few times until you can easily fill the tweezers points. You can easily direct a drop or less of solvent exactly where you want it.

Apply even smaller amounts by dipping toothpicks into the solvent.

Tech Note. Several Minolta film camera models from about the late 60's on, used light seals with the adhesive applied   After applying solvent to the old seal and waiting 10-20 seconds. Many times, with tweezers you can carefully get under the foam seal and  get to the tape then just peel the entire seal strip off in one piece.

Door channel seals vary in width and a custom tool can easily be made to help remove and push the old foam out.  Take a Q-tip (cotton swab) and cut off one of the tips, then using small needle nose pliers squeeze the end carefully until the width fits the door channel. You can easily cut that end with an Exacto to a shape that works for you.

The first seals I remove are the door channels.  Fill your #5 tweezers points with solvent and carefully moisten the foam in the channels.  You must be more careful around the counter actuation lever opening (upper right hand corner door channel on many cameras) as you do not want to apply solvent to the interior of the camera.

After a couple of minutes the residue can be easily removed by pushing it into a pile with a toothpick. The residue will just pile up in the channel and can be picked out and wiped out.  Wrapping a Kimwipe around the straight tweezers points and dipping that in solvent works quite well in the channels also. We know of technicians who prefer an old toothbrush and would brush out the softened foam. Clean. Clean. Clean.

Now clean the door hinge seal area.  Here you can lightly moisten q-tips to apply solvent and then wipe and clean away the residue.

Last, clean the mirror cushion area Here you must be extremely careful.  If the focusing screen is easily removable, remove it. Make sure that no pieces of the old cushion fall onto the focusing screen. If any anything contacts the focusing screen it will most likely damage it permanently. We have never found any way to clean a light seal damaged focusing screen or mirror so it would look like new.

Carefully pick and scrape at the remaining cushion towards the lens opening.  Some mirror cushions are installed with peel and stick adhesive. Sometimes it will just peel off.

Prepare yourself.

Be rested and relaxed.

You do not have to hurry the install, but be prepared.

All I am trying to do here is prepare you for a somewhat precise service that generally requires 10 minutes or less. Installing seals go very fast after the camera has been cleaned. You will be surprised how quickly you will finish. If you continue installing light seals, say for your friends film cameras, you will be quite proficient after 5 to 10 installations. 

Qualify yourself.

 
This is a technical task however not a difficult task to accomplish.

 You should have steady hands and not be frustrated easily working with small objects, tools and tweezers.

 As far as the difficulty level working on photo equipment and using a 1 - 10 scale,  installing seals is a 3.

 The skill level required goes up if you are removing covers.

 You would know your skill and ability better than anyone else.

 It is very difficult to damage your camera performing this service.

I have trained many photo technicians and for the most part, women had better hand eye coordination, learned quickly and became proficient faster at camera service than men.

Installation

 

New to installing light seals? I recommend starting with the shorter seals first, such as the door hinge seal. This is a rather short piece and can be handled easily. I do not recommend starting with the mirror cushion seal first.

 

The replacement seals are cut to exact lengths.  Stretching of the seals during installation and around corners will result in some left over at the end which can be trimmed with an Exacto knife or razor blade.

 

Because of the type of adhesive used, some door hinge, mirror cushion and other seals do not stretch during installation. Typically, the thinner the width of the seal, the easier the material can be stretched and or torn.

 

 Understanding wetting agents as a adhesive delay. 

When installing seals that already have the adhesive applied requires a different technique than applying seals with no adhesive.

Delaying the adhesive from setting /sticking immediately upon contact is a must.  You have less chance of a successful install if do not use a wetting agent. You have a limited time before the seal has to be placed and positioned.  Alcohol has the shortest working time, hand sanitizer is the longest and water is in between.

I personally found water is the best. It does not react with the adhesive and gives a workable handling time before the adhesive bonds.  I checked the adhesive bond, by applying water to the adhesive and then applying the seal material to smooth surface plastic laminate and another sample to painted steel. After the wetting agent dried all foam was damaged somewhat when removal was attempted. 

We found three ways to delay the adhesive,

1) alcohol

2) water / moisture

3) hand sanitizer, alcohol based with absolutely no additives, no fragrance, no moisturizers , ect 

Preparing your equipment. 

Remove all the old seals and spotlessly clean where the new seals fit.

Installing the door channels can be the most challenging. When installing the door channel seals,  always start at the door hinge side and work towards the latch side of the camera. Many ways of applying the door channels or any seals for that matter will work, however what I am just trying to relay what worked best for me.

If I can see the upper door channel completely, fine. If not, I loosen the top cover screws first and check again.  Most of the time the top cover will not have to be removed but sometimes yes. I check the bottom door channels for corner damage, remove the bottom cover if necessary. If the door closes and latches unlatches easily usually that means the channels are OK.  If any of the door channels show a little damage, all you need to do is stretch the seal a little bit and it will fit easily in the damaged channel.

USCamera Tech Note. Camera manufacturers install light seals with the covers. Many times, when the top and bottom covers are installed, it will obscure a clear view of the door channel making it more challenging to install those seals. Impact Damage. Over the life of many film cameras, they are dropped. Sometimes at the bottom cover corners.  This can damage the door channel at that location.  This will constrict that channel some making it a little more difficult to install the seal. Never try and straighten the channel, it will break, see below.

I cannot say this loud enough. RESIST the temptation to insert a screwdriver or ? and carefully attempt to straighten the bend in the door channel.  Many camera bodies are cast aluminum and some are plastic. You will break off the casting before you believe you have put any pressure on the channel. Lesson learned from experience.

If working on an RB / RZ back and insert, I remove the top and bottom covers.

Using water as a wetting agent.

Holding the seal with wet fingers, I remove the backing and apply water liberally (not soaking) to the seal by dipping clean fingers in a glass of water and gently guiding / carefully pulling the seal around / through my wet fingers.  Colorado has a dry climate.  I can take a wet seal and place it, remove it and place it again without damaging it.  However after the second time if you have not placed it correctly, rewet the seal. The results I describe are from testing seal placement on clean door channels of a test camera body.  After wetting, I found I had about a minute or so, to place the seal in position before the adhesive started to become tacky. If I placed the seal in the channel and removed it, water would need to be re-applied as the looses moisture when contacting the channel.

Installing the seals.

As I said at the start, beginners should install short seals first, the channel seals and the mirror cushion last. It is of course entirely up to you.

I am assuming you have confirmed the channels are not damaged. Also, you have loosened screws or removed covers to have full access to the channels and other areas requiring seal replacement. You should have the tools you need. 

Below I am explaining how I install seals. Remember how you install the seals is up to you, the following is what works for me.

I place the equipment flat on a tech work mat so is does not slide or move around easily. I take a square toothpick and trim it so it perfectly fits the door channel of the camera I am working on. Make a couple of these. I have several toothpicks, q-tips I have made before. I also use pointed bamboo stick a lot to push the seal or hold it in place

Lay out the light seals.

I am right handed. For this seal piece, I rotate the camera so the hinge is on my left.

Select the top door channel seal (which is now on the bottom) starting at the hinge side, with backing on the seal, I hold it up to the channel and size it from the beginning of the channel to the counter lever opening. Then I cut that seal length. The remainder of that seal will fit the rest of the top channel.

I wet my fingers, remove the backing on the short seal and moisten it, making sure that the edges of the adhesive are wet. Then I hold one end of the seal with tweezers and place it in the channel, holding the end I just laid in place with a toothpick, I lay the rest of the seal in position.  Again with my fingers wet with water, I remove the backing from the remaining top channel seal and moisten the seal. Then starting at the other side of the counter lever opening and place the end of the seal at the in the beginning of the channel and press about 10 -15 mm of the seal in place with a trimmed toothpick or bamboo stick. Then I hold the other end of that seal with tweezers and guide the remainder of the seal in place. Then with the trimmed toothpick or bamboo I carefully press the seal into the channel. Now | perform the exact same service installing the bottom channel seal. I install rest of the seals used on the back cover. Then I close the back cover to seat the seals in position.  Last I install the mirror cushion. Now I open the back cover and leave it open until the seals have completely dried. In the Denver area about 4 - 6  hours.

Through experience we have found some seals would like a little adhesive keep them in place.  Goodyear Pliobond is great contact cement for this purpose.  Remember, you are attaching small pieces of foam to a precise instrument.  A toothpick works great or applying a just the right amount of adhesive to the foam or the location where the foam will be placed.  Never try to apply adhesive to any area near the focusing screen.  Always apply the adhesive to the foam first.  Should adhesive somehow get on the screen it will permanently damage it.

As Always ............Good Luck

the USCamera Team

 

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