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 Post subject: Refractometer info?
PostPosted: Tue Aug 19, 2008 6:41 pm 
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Hi everyone,

Here are some pictures of a Rayner refractometer I purchased a while back. I got it for next to nothing, but it seems to be in good condition and I'd like to use it. I've done a few readings with known material, and the numbers were what I expected.

I'm hoping you guys can tell me a little more about it.
My questions are:

Is there a model name or number? I found some numbers on the bottom, but nothing else. There is basically no documentation with it, just one sheet with some basic instructions that make mention of different light sources.

Does this model have a built-in yellow filter? (I'm guessing not) Where would I get a filter if I don't invest in a light source? There are two empty slots in the case, I'd guess they were for some sort of accessories such as filters? Right now I just use sunlight through a window, but the readings seem ok...(i.e. 1.768-1.772 on a sapphire I cut - just some spot readings).

The glass hemicylinder has a small ding in it, but it doesn't seem to affect anything so far as I can tell. Would there, however, be some way to replace it?

Anything anyone might know would be appreciated. Pictures below:

Image
Image
Image
Image

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PostPosted: Tue Aug 19, 2008 7:04 pm 
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Hmmm ... appears to be missing the polarizing filter and the yellow filter. Of course you can always use the salt-in-a-candle trick for your sodium-light source 8) .

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PostPosted: Tue Aug 19, 2008 11:44 pm 
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What you have there is a Rayner S (scale ) model. A somewhat late but not the latest version. This was the model before the Dialdex which has a green finish. They also made one later series of the S that looked very much like a Dialdex but did not have the dial. There was also an earlier version of this one that was essentially identical but had a black wrinkle paint finish.

There is no built in illuminator. Rayner did make a sodium lamp illuminator for these. They also later made an LED illuminator but they were not built in.

MoDo is correct. You need to get a polarizing filter and an orange filter, either glass or plastic. A Wratten Red 23A is a good one which will block most wavelengths shorter than the double D line but does nothing to the longer ones.

You could also get a bandpass interference filter right on the double D line..

If the bottle is empty you can get a refill from www.cargille.com

That is an excellent refractometer with absolutely nothing to apologize for.
You have to adjust the eyepiece so that the scale is in sharp focus. Sometimes on these models if the lubricant gets old the whole eyepiece may try to unscrew lower down. In that case you need to very carefully remove and perhaps freshen the lubricants. You can lock the lower thread with a very tiny dab of Elmers glue and leave it alone for a couple of days. If the helical thread grease has dried out and gotten stiff very carefully remove it with lighter fluid or similar on a well washed cloth and not too much solvent. When you have gotten the old stuff off you can use some teflon synthetic grease to replace the old lube. VERY SPARINGLY.
You may need to loosen three little centering screws to remove the eyepiece from the focusing mount.

Check its calibration with known stones. or send it to me and I will check it with cal plates and a sodium lamp. Or buy the cal plates from Doos.

If the scratch doesn't interfere with the readings then leave it alone.
If the scratch does interfere then you can consider repolishing it but there are a variety of pitfalls associated with the procedure. It depends how deep the dig is. The high RI glasses used to make the measuring prisms are soft. You need to keep them clean because the contact liquid can attack them. Most books recommend putting a little rub of vaseline on them after cleaning off the contact liquid. I think this is good advice and do it on my refractometers.

Recalibration of this model is not terribly difficult.

I don't think Rayner is in the business anymore. The British Association were their sales agent and they have not listed Rayner refractometers in some time now.


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PostPosted: Wed Aug 20, 2008 12:25 am 
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Thanks MoDo and Gene,

That pretty much confirms what I thought...good to hear it from someone else.

Gene, where can I find filters? I'm assuming a simple plane polarizing sheet will work for one, where does a Wratten 23A come from?

I've already gotten fresh fluid from SPI (Cargille's alter-ego now, apparently...). What a nightmare that transaction has been, but that's another story.

The divot in the glass is deep, but only in one small place. I've already polished it a bit with some Cerium oxide, but the one chip won't polish out. Otherwise, it's in good shape.

I might take you up on checking it out, Gene... I love to use older refurbished tools...I'd like to be able to use this one.

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PostPosted: Wed Aug 20, 2008 12:54 am 
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Quote:
Gene, where can I find filters? I'm assuming a simple plane polarizing sheet will work for one, where does a Wratten 23A come from?


Wratten used to be British about a hundred years ago or more. Then George Eastman bought the company and it was part of Kodak forever. Well almost.
More recently they have sold the business to the Tiffen filter company who know make and sell Wratten gels and cells (huh huh)

You can go to any camera store or camera show and find them. You want a round one that will fit into the eyepiece. 15mm diameter or so.

The ebay seller bjomejag can make a cool interference one for you.
there also is an ebay seller called buyrightauctions that has had them on and off. Almost any orange filter will do. Roscolux has plastic ones. You can buy those in onesies from the McCrone Research Institute store in Chicago.
Dr. Bill might be able to help you on that one too.

I am sorry to hear that Cargille is trying to go the way of all flesh. Not actually surprised either. If Rayner is gone why shouldn't Cargille be gone.?


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PostPosted: Wed Aug 20, 2008 9:59 am 
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Huh? I just ordered some liquids from Cargille and the transaction was really easy. All arrived later in the week. Placed my order over the phone with them. They also answered a question promptly by e-mail. Saw no reference to SPI? Could you have been dealing with a reseller maybe?


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PostPosted: Wed Aug 20, 2008 10:36 am 
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Hi,

As for the filter, I would suggest buying a narrow bandpass interference filter. You can get them from around USD 50.00 at Knight Optical in the UK. Get the 589.6 one with 3nm bandwidth and mount it in front of the light source. Can't get much better or easier than that.

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PostPosted: Wed Aug 20, 2008 11:12 am 
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Carrie wrote:
Huh? I just ordered some liquids from Cargille and the transaction was really easy. All arrived later in the week. Placed my order over the phone with them. They also answered a question promptly by e-mail. Saw no reference to SPI? Could you have been dealing with a reseller maybe?


I wish that I'd just phoned them. Due to the time difference, I tried to order online and was sent off one site to an on-line ordering system. Whoever it was, the problem wasn't with their service so much as it was with the way they deliver. They insisted on using Fedex Home delivery, which will apparently only deliver to residential addresses during business hours, when everyone is at work. Their nearest office is 70 miles away, and I wasn't willing to go pick the package up after paying a bunch to ship it. Since Fedex couldn't get a signature, they sent the parcel back to the shipper...etc... A big mess, and still working on getting the billing corrected.

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PostPosted: Wed Aug 20, 2008 11:18 am 
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Doos wrote:
Hi,

As for the filter, I would suggest buying a narrow bandpass interference filter. You can get them from around USD 50.00 at Knight Optical in the UK. Get the 589.6 one with 3nm bandwidth and mount it in front of the light source. Can't get much better or easier than that.


Thanks Doos. Would you care to elaborate on the reasons for your recommendation? I'm not questioning it, mind you, just trying to educate myself. :D

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PostPosted: Wed Aug 20, 2008 11:42 am 
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Hi Kevin,

The refractive index of gemstones is determined by measuring with a specific light source as I'm sure you are aware of. This sodium light can be mimicked with filters. These filters come in different graduations/qualities. The goal is to create light that comes closest to the Fraunhofer D-Line (actually there are 2 of them ..). Getting a filter around the 589.6 nm line which blocks all light except that wavelength will get you very sharp refractive index readings.

These filters come in various bandwidths. The narrower the bandwidth, the better. 3nm is better than 10 nm bandwidth, but is also more expensive (if USD 50.00 is regarded as expensive).

Hope this quick summary helped a bit.

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PostPosted: Wed Aug 20, 2008 9:34 pm 
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Take a look at this auction
Pretty close.


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PostPosted: Thu Aug 21, 2008 9:18 am 
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Hi Kevin,
i've one of that refractometer too and it works perfect.
what it's seems wrong with yours is that someone has painted the ocular in silver :? while it originally comes in black plastic. i am wrong?
take a look
obviously this wouldn't affect it's functionality.
ciao
alberto

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PostPosted: Thu Aug 21, 2008 3:20 pm 
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Rayner (nee' Rheiner) did that.


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PostPosted: Thu Aug 21, 2008 3:37 pm 
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G4Lab wrote:
Rayner (nee' Rheiner) did that.

Seriously Gene? it's seems orribly painted.....
ciao
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PostPosted: Thu Aug 21, 2008 6:20 pm 
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Believe it or else :D


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