How Do You Tell If A Refractometer Is Quality?

[Danno]

I was looking around on the net for the cheapest refractometer. I finally deciseded to look on eBay. I found this: Refractometer

It is so cheap, it makes me question quality, but then again, that is something I COULD afford.

 

[SkiFletch]

I too have a no-name ebay one. Works great. A refractometer is kind of tough to cut corners on and really screw up. You can add bells and whistles to make it expensive, but the prisms that make them work are usually all made well. Even the cheap-o refractometers are maybe 1ppt off, which isn't that significant

 

[ddm18]

Hi,

Sorry to hijack, but a similar-ish question: on eBay (and elsewhere), I've seen refractometers listed as being for other purposes (a quick eBay search now has fruit juice, wine and honey among the top 5 results) - they all look the same, but are they? Presuably they do the same job (and the ones listed above all seem to be from the same seller), but are they set up differently?

 

[adambrum]

There are different types of refractometers for checking different fluids ( i used to use one for checking soluble oil) a refractometer is a type of instrument what you need is one for checking salinity

 

[SkiFletch]

Yeah, its a similar concept and method, but a different implimentation. A refractometer works by passing light through a solution which changes its direction. The light is then focused with a prism on to a scale calibrated for what you're measuring that you then read. Different molecules (sugar, oil, salt, etc) have different prisms and different scales. So while the concept is the same, they are not inter-changeable.

 

[atmmachine816]

Uh since there's a topic already for refractometers to calibrate most to measure sg you just add a few drops of distilled water and bring the line down to zero right?

 

[andywg]

Uh since there's a topic already for refractometers to calibrate most to measure sg you just add a few drops of distilled water and bring the line down to zero right?

In theory yes.

In practice no.

Most cheap refractometers (ones we can afford) tend to be a little bit out over the whole scale. The best way to calibrate is to purchase or mix a known salinity solution, and calibrate up to that, rather than down to pure water.

 

[Danno]

SkiFletch noted this article before in my journal. Make your own calibration liquid

 

[atmmachine816]

ok thanks