Through the microscope

Posts tagged ‘Microscope’

Video

Displacement reaction under the microscope

The first video shows what happens when copper wire and silver nitrate are allowed to react under the microscope. The video was recorded using Gladys, the Zeiss universal with transmitted light. Because the silver formed is not transparent it appears in silhouette. The pink background was achieved using a rheinberg filter.

The second video shows the same reaction viewed under a stereomicroscope using incident light. The magnification is not as great using the stereomicroscope but it is fun to see how the different types of microscope give a different perspective on the same reaction.

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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.

dunscombe new pinion

New pinion (right) to replace original worn pinion

aab_1624

Dunscombe of Bristol

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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!

Making Rheinberg Filters

Today I have been making Rheinberg filters.  Rheinberg fiters are a way of optically staining specimens, they were developed by Julius Rheinberg whose work was published in the Journal of the Royal Microscopical Society in August 1876. He was quite a clever chap. Inventing them was quite an achievement, making Rheinberg filters isn’t quite as tricky…..

Things you’ll need: Either some metal punches and a mallet to bash them with or some craft punches (the kind people use for card making) I prefer craft punches; a mat on which to bash things so you don’t ruin your floor or table; a pen that will write on plastic, an old filter, laminator pouches (gloss) and a laminating machine set on hot;  scissors, black card or electrical tape, some coloured gel film – the kind they use for theatre lighting is good. I got a sample pack for a couple of quid. You can use other clear, brightly coloured plastics sheets. Use your imagination and poke around your “useful things” cupboard or drawer (I know you have one).

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Stuff for making Rheinberg Filters

 First, make some simple dark ground patch stops to help you determine what size your Rheinberg filter centre stops should be. Pop a laminator pouch through the laminating machine and you will have some nice sturdy plastic sheeting to start off with. Alternatively, just cut up some stiffish, clear plastic sheeting. You need to cut out circles of the clear plastic that will fit neatly into your condenser filter holder. My filter holder is 32mm diameter, I just draw around an old glass filter. You don’t need  perfect circles, just make sure the disc won’t fall through the filter holder.

Now you have clear plastic discs on which you can put your dark ground patch stops. Use some black electrical insulation tape, or vinyl, or even a piece of black card. Punch out circles of various sizes using your punches and stick them in the centre of the clear disc. You centre them by eye. You should make a range of discs that look like this:

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The sizes of the black central stops I made were:

A – 7.5 mm

B – 10 mm

C – 12 mm

D – 14 mm

E – 16 mm

F – 18 mm

G – 20mm

Now you need to decide which stops work best with each objective. Put a slide on your microscope. Something suitable for dark ground like diatoms, a stained section won’t work.

Open the condenser iris and the field iris and rack up the condenser as high as it will go. Place each of the patch stops in the filter holder in turn and record which patch stops produce the best dark ground with each objective. You’ll end up with a chart that looks something like mine:-

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From this I can see that the best size patch stop to make will be E (16 mm). It should cover all bases, although I’d probably make one of 14 mm as well, just to be on the safe side.

Now I know what size patch stop to make it’s on to the fun part….

Making the Rheinberg filters:

The central stop will determine what colour background your image will have. The outer ring will determine what colour your specimen will be “stained”. A blue central stop with an orange ring around it will produce a blue back ground with orange specimens. The supergel samples I have tell you what transmittance the filters have. 10% transmittance or less works best for the stops (that’s very dark, so dark you can’t read text through the filter). Higher light transmittance is better for the outer rings.

Cut out some central stops of coloured film using your punches. I determined that 16 mm stops would work best with my Vickers objectives so that’s the size I punched out.

Cut out some coloured circles the size of your filter holder (32 mm for me) and then punch out the centres so that you will be able to place the coloured stops in the hole that’s left. The central stops and holes need to be cut out cleanly. There shouldn’t be any gap between the central stop and the outer ring/annulus when they are put together.

Annular rings and stops

Annular rings and stops

Now carefully place your rings and stops into a laminator pouch and laminate them.  Cut them out with a pair of scissors or a punch (do not use your spouse’s dressmaking scissors for this). You’re done. You have Rheinberg filters.

If you use a coloured stop with a clear outer ring you will get a coloured back ground and an unstained specimen. Sometimes it looks better than when you use a stop + ring. If you laminate the rings and stops separately you can try out lots of different colour combinations. A black centre stop with a coloured ring can also look very pretty.

Here are some images I took of Polycystina on my beloved old Vickers microsc0pe using my home made Rheinberg filters, all using a 20x objective. The photographs don’t do the images you see down the microscope justice. They look excellent viewed through the microscope . As I’ve mentioned before, I’m not really very good with cameras yet!

Pink central stop, orange annulus

Pink central stop, orange annulus

Blue central stop, pink annular ring

Blue/green central stop, yellow annular ring

Dark ground – black centre stop

You can see that the resolution is somewhat better with the dark ground than with the coloured stops and some colour combinations work better than others but it’s great fun to experiment with. The choice of colour combinations is almost unlimited. I shall certainly be making more and trying them on some of my other microscopes.

Have fun with your Rheinberg filters!

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