Through the microscope

Archive for the ‘Restoration and cleaning’ Category

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/

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