Through the microscope

Archive for the ‘Restoration and cleaning’ Category

Spencer juggy rescue

I bought this Spencer jug-handled microscope some time ago, at first glance it doesn’t look too terrible, a broken mirror holder and a missing mirror; but if you look again you will see that the poor thing has been spray painted black from top to bottom. The objectives, the coarse and fine focus knobs – everything is painted. This is a serious rescue, I have never had to use paint stripper on a microscope before but this calls for desperate measures. As you can see in the last picture, so far not too terrible, there is hope. I have stripped the black paint off the focus knobs, and underneath the paint the coarse focus has polished up pretty well. I have to de-corrode the other parts and see if I can get a polish on them good enough for hot lacquering. It’s not so much a restoration as a salvage operation, but I have a soft spot for jug handled microscopes Wish me luck.

A restored brass microscope

This is the piece I have practiced and learned lacquering on. I hope you agree it is a dramatic improvement!

It is a Dunscombe microscope. Dunscombe was the son-in-law of Braham and took over his father-in-law’s optical business. In fact, there is still a Dunscombe Optician’s in Bristol UK where they lived and worked.

This microscope has been stripped, cleaned, polished, straight grained and lacquered about 20 times over the last couple of years while I have practiced the art. I have to admit that I intend to strip it again because there are a couple of pieces that are not quite up to my exacting standards. For now it will stay as it is. I have other microscopes to work on and I have had enough of this particular microscope for a while.

 

A new screw was made for the top to replace the nasty steel wood screw that had been shoved in there and two new screws were made to hold the microscope onto the foot. A new rack was cut on the milling machine and a new pinion was also made as the original rack and pinion were badly damaged and unusable. The stage was chemically blackened using a commercially available selenious acid based product. Not too shoddy I think.

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New pinion (right) to replace original worn pinion

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Dunscombe of Bristol

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Hot lacquering of brass

Here it is, my first perfect piece of lacquering. It’s been six months since I started this mission. I have messed around with lacquer recipes, I have altered resin proportions, I have tried different polishing methods, different cloths and brushes, different temperatures and finally I have success.

One of the keys to success has been a sunny day – not generally something I can control but it certainly makes a difference.

Getting the finish on the metal right has been challenging. I don’t want the microscope to look like a reproduction but I don’t want it to be full of pits and bumps either. Restoring an antique microscope has to be done sensitively, I’m going for old but in good nick, not brand-new-reproduction made in a  Chinese factory.

I’m very pleased. Now I have to do the rest of the microscope to the same standard.

No flash was used on these pictures. 

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My first attempts at lacquering

This is one of my first attempts at re-lacquering a Watson Praxis. The old lacquer was almost non-existant so I stripped it off using ammoniated cleaner (nasty stinky stuff), then sanded, polished and grained the tube before applying lacquer.

The lacquer is a turmeric and shellac based lacquer. It’s okay but I feel it needs to be tougher than it is. It doesn’t look like it will last 100 years. This week I shall be trying to perfect my lacquer recipe by adding some resins, wish me luck!

Re-lacquering of Watson Praxis Tube

Re-lacquering of Watson Praxis Tube

Recreating Western Lacquer using Historic Recipes – Day 1 | Marianne Webb

I have been playing around with metal lacquer for the last few weeks. I have desperately been trying to figure out how the hot lacquering of microscopes was done. Information on lacquering metal is rather hard to come by and I want to use the original techniques, not modern lacquers. 

I have tried various recipes with varying degrees of success, in the next few days I should be receiving some sandarac and elemi in the post. I think these resins may be my secret weapons.

As soon as I get something close to perfect I shall post a picture. In the meantime here is a link to a very nice blog I stumbled upon; not metal lacquer, but very interesting just the same.

Recreating Western Lacquer using Historic Recipes – Day 1 | Marianne Webb.

Baker Series IV fine focus reconstruction

Hello chaps,

The Baker series IV is now returned to its former glory, almost. The fine focus was broken because a small pin had sheared off. To fix it you will need a lathe, or a friend with a lathe, patience, grease and some small tools.

First, remove the old broken pin. It’s a tight fit so you may have to bash it out with a hammer. Next, ask your friend, who has a watchmaker’s lathe, to make you a new pin for the fine focus mechanism.

Broken Baker pin

Broken Baker pin

Next, insert the new pin where the old pin used to be, It can be seen just to the right of the screw head in the black, central region.

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Hang the widget on the pin and grease the tracks for the ball bearings. Stick the ball bearings in position.

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Widget hanging on pin, ball bearings

Now you must make sure that the notch in the widget will take the little square nubble on its opposite piece (I hope you’re enjoying the technical terms). This is very important, if the nubble isn’t sitting on the notch then the fine focus will not work, the fine focus relies on pressure from the stage carrier as well as the action of the spring at the bottom to return.

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Attempt to put the two pieces together. You will find that half of the ballbearings pop out and your hands will be covered with grease (and cat hair if you live in our house). Make sure the cat hair doesn’t end up inside the fine focus mechanism, it won’t do it any good.  If your Baker Series IV has a cage to keep the ball bearings contained and aligned sing “Hallelujah!” because it will all be much easier to put back together.

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If your ball bearings pop out, here’s a video of my wonderful husband showing you how to pop them back in.

Now you can put the spring back, put on the top and bottom plates and reassemble the microscope.

The next picture shows the base plate which contains the spring and allows the fine focus mechanism to return.
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And here she is, the fixed microscope. I’m still not completely happy with the paint work but at least she works now.

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Baker Series IV paint matching

Baker Series IV paint matching

The Baker Series IV is a rather unusual colour, a sort of greenish grey with a metallic sheen. I am reliably informed that Baker used a cellulose paint. The colour and sheen is not easy to match unless you’re willing to spend a lot of money on a colour matching service at a fancy auto shop. As a car colour matching service would cost me more than I paid for the microscope, I plumped for muddling through on my own.

I have had a lovely German exchange student for the past week and I didn’t want to play around with paint too much in case the smell upset her, but I did manage to prepare the microscope for painting by scrubbing the rusted spots with wire wool dipped in de-corroder. Now I am free to stink up my house again, so I have prepared an essay on “what I did at the weekend”.

First, I braved a trip to Hobbycraft. Within five minutes of entering Hobbycraft I am usually ranting in the style of John Cleese. I HATE HOBBYCRAFT. Everything in there comes in kit form because Hobbycraft don’t seem to credit their customers with any imagination or creativity. The kits they sell are usually missing something important and the staff in there, although very pleasant, are powerless to help you. I have been in there on numerous occasions over the years asking why they sell fat quarters of quilting cotton and quilt wadding but no quilt backing. The only good thing about their appalling sewing range is that my loathing of Hobbycraft led to my discovering a very lovely quilt shop in Bristol called Poppy Patchwork. Visit them, they’re wonderful. I’ll put in a link at the end.

Back to the Baker Series IV : In Hobbycraft I managed to find some Humbrol enamel paints. I chose a variety of greenish/grey paints and a few others (because my husband was paying).
I painted a small area of the microscope with each of the greenish/grey paints and a couple of mixes.

In the photo above you can see (from right to left)
MET 53, matt 224, matt 75, satin 163, a 1:1 mix of matt 224 : MET 53 and right on the toe of the microscope you can just about see a 10:1 mix of matt 224 : MET53. None of these were perfect but it gave me an idea of where to go next.

After playing around for some hours I discovered a pretty good mix. Two small brushfuls of Met 53 mixed with one brushful of satin 163, plus two drops of black gloss 21 and one drop of green 75. The sheen is not quite right but the colour is good. Hopefully when it is polished up it will be a pretty good match. I’ll post more pictures when it is finished.

Poppy Patchwork – http://www.poppypatchwork.co.uk/

Fixing a rusty iris diaphragm on a Baker Series IV microscope

I recently bought a Baker Series IV, I wasn’t planning on buying one but my friend, Merv, convinced me that I should. I don’t take a great deal of convincing because I’m a sucker for any microscope. I think the persuasion went something like this.

Merv said:

“There’s a Baker Series IV for sale, they’re nice microscopes.”

– I bought it.

It was cheap but it’s not in a great state.  It has rust patches and bubbles in the paintwork. Bits that should move freely are stiff and bits that shouldn’t move at all wiggle. The usual second-hand microscope problems.

This time though there was a more serious problem. the iris aperture was rusted, badly rusted;  it’s also a fiddly horrible design, the edges of the iris blades are bent up and the whole thing is quite fragile. I don’t like taking iris diaphragms apart at the best of times and I definitely didn’t want to take this one apart so I did what any sensible human being would do. I called my friend and asked him how to fix it.

“It’s simple” he said (he says that a lot) “isopropanol, de-ruster, isopropanol,  WD40 and a soft toothbrush”

Guess what? he was right, it was simple, so I thought I’d post it here, in case anyone else finds it useful.

 

STEP 1 – Observe the horrible rustiness of my aperture iris. I attempted to remove the iris diaphragm carrier from the microscope but I failed because I couldn’t turn the screw I needed to turn. I have hypermobile joints and a rubbish grip, my husband was at work so I couldn’t get him to do it. I had to  work with it in situ. I popped some absorbent cloths underneath the carrier to protect the field iris/condenser lens beneath and continued.

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STEP 2 – cover the rusty iris with isopropanol and give it a gentle scrub. I didn’t have a small enough toothbrush so I used a foam camera sensor cleaning widget. I prefer them to cotton buds because they don’t leave fluff behind. They’re more expensive than cotton buds but I use them quite a lot in delicate areas.  Quite a lot of surface rust has come off already, see?

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STEP 3 – after the isopropanol has evaporated cover the iris in de-ruster. I use Renaissance Metal De-Corroder.

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The Renaissance blurb says:

Treatment selectively ruptures the bond between base metal and corrosion layer, reducing rust to a sludge which is easily wiped or brushed away. Clean-water rinse stops the process.

Even relatively prolonged immersion over several days has no significant effect on sound metal, thus giving the conservator complete control over the process – and freedom from it.

The totally benign nature of the product eliminates work and health hazards associated with common de-rusting systems such as those based on phosphoric and hydrochloric acids.

I can’t fault it, but it is expensive, so use an alternative if you wish to. In the next picture you can see the Renaissance De-corroder doing its thing. I put it on with another foam camera sensor cleaning tip and left it to work for an hour or so. I gave it a gentle scrub every now and then. It’s all very scientific.

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Step 4 –  Rinse off the metal de-corroder with water, allow to dry (use isopropanol to help it on its way if necessary) then give the iris diaphragm a squirt of WD40. Give it a wiggle and smile contentedly as you watch the clean, de-rusted iris moving freely. Have a cup of tea then contemplate how you’re going to tackle the rest of the microscope.

EDIT: Please see comments section for helpful advice regarding WD40 and oil on iris diaphragms.

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Thanks to Merv Hobden for his advice and guidance.

http://www.picreator.co.uk/articles/1_about_us.htm

 

 

Gallery

Look at my shiny microscopes!

Today I have been polishing two microscopes that had chipped paint work.

I started by lightly sanding around the chips  with 1500 grit paper, I filled in the chips with layers and layers  of hammerite smooth paint (sanding lightly between each layer of paint to make a key for the next coat). When the chips were filled and level I sanded the whole microscope again with 1500 grit sand paper to form a key and sprayed it with spray enamel (masking off delicate areas).

I left the spray enamel to dry for a few days then went over the microscope with T-cut, next I used Meguiar’s ultra cut which gives a really high sheen and finally I applied a finishing polish. Meguair’s ultra cut is bloody marvellous stuff. I’m pretty chuffed. The polarizing microscope started off with no paint at all on its feet. The phase scope’s paintwork was in better condition but it had a few large chips on the base and on the stand.

Aren’t they shiny?

Tomorrow I shall post pictures of the cobwebs I found in the 45X objective, I promise!

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