Through the 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.

Image

 

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?

Image

 

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.

Image

 

 

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.

Image

 

 

Thanks to Merv Hobden for his advice and guidance.

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

 

 

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Comments on: "Fixing a rusty iris diaphragm on a Baker Series IV microscope" (5)

  1. Mike Andrews said:

    Lovely job. Truly. I hope you are aware that WD40 is not a lubricant, and that as the solvents evaporate from it, it will turn gummy. It is designed to displace water (“W D”), and works well at that, but you may want to replace it with progressively thinner oils, and eventually with something that will completely evaporate. I find my irises work best when totally dry.

    Best regards,

    Mike Andrews, W5EGO WWME Oklahoma area executive team

    >

    Liked by 1 person

    • Thank you! I wasn’t sure whether to oil it or not. Opinions seem to differ on whether one should oil or not and i was not aware of the need to reduce the thickness of the oil gradually. My CTS diaphragms all run dry.
      The WD40 tin says it leaves a protective residue to limit furthur water/rust attack. They don’t mention stickiness!
      I shall pop some oil on tomorrow and replace it gradually as you suggest.

      Liked by 1 person

  2. It’s good to see you back, Penny!
    I wonder if your potion would work on an antique metal piece, to reveal the once beautiful engraving… (I don’t care if i reduce the value, I’d rather see the engraving than the black stuff…)
    Hugs,
    teagan

    Like

    • Hello lovely lady!
      I’m pretty sure it would work on an engraving.. The Renaissance metal de-corroder is very safe and I have seen articles written by people who have used it on ancient swords without any harm being done. It’s expensive but you can buy a mini bottle if you don’t have a huge amount to do. You can dilute it as well, I don’t bother because I use tiny amounts.

      Are you sure the black stuff is corrosion rather than tarnish?

      Like

  3. I like the sound of that Renaissance metal de-corroder, that sounds very useful stuff indeed.
    Nice to read Mike’s comment about WD40. He beat me to it 😉

    Like

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