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 Post subject: Measuring Silicone Rubber R.I. - Cheap Refractometers?
PostPosted: Fri Feb 08, 2019 12:38 pm 
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Hi all, first post here so please pardon any naivety. I've tried to do as much searching/reading as possible here on the forums and elsewhere, but still have a few questions:

I am working on using clear molded silicone rubber as a lens, and would like to measure refractive index of some material plaques I have. They are 50-70 Shore A durometer parts out of a polished mold. My thought was to cut small samples from the plaques, and take measurements using an inexpensive gemstone refractometer (this Kassoy unit, for example: https://www.kassoy.com/Refractometers/G ... ometer.asp).

I don't need super high precision, second decimal place +/- 0.05 or so is probably fine for my needs. Silicone rubber R.I. is on the order of 1.35-1.45. Do I need to use real refractometer fluid (1.79-1.81), or can I substitute with some immersion oil (or household oil) of a lower R.I.?

Feedback appreciated, thank you!


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 Post subject: Re: Measuring Silicone Rubber R.I. - Cheap Refractometers?
PostPosted: Sat Feb 09, 2019 3:43 am 
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That sounds like it should work in principle, both the refractometer and the lower RI fluid.

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 Post subject: Re: Measuring Silicone Rubber R.I. - Cheap Refractometers?
PostPosted: Sat Feb 09, 2019 3:15 pm 
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Thanks for the feedback, any suggestions of what to use in place of the RI fluid?


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