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cheap Chinese refractometer

Post #1 made 14 years ago
by shibolet
hi guys,
i bought this cheap chinese refractometer on ebay.
it seems to work fine except for one thing: it has a dig. plato scale and an SG scale and they don't seem to agree with each other
that is, if the plato scale says 13.1 the calculators tell me that that's 1.053 SG, but the refractometer SG scale says 1.051.

i remember reading/hearing somewhere that i should be following the plato scale and disregarding the SG scale. can anyone corroborate this?
Cube:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:

Post #2 made 14 years ago
by hashie
When I had a refrac, it was the same. Nothing made sense when compared to brewing software calculators.

I ended up putting it in the bin, it's much easier to rely on a good hydrometer, than to try and fudge figures from a dodgy refractometer.
"It's beer Jim, but not as we know it."

Post #4 made 14 years ago
by stux
Many of the "cheap" chinese refractometers on ebay are the same ones that reputable homebrew stores sell, I believe.

BUT as far as I'm aware, the SG scale on these refractometers is rubbish

This is confirmed by morebeer on their refractometer page

http://morebeer.com/view_product/18739/" onclick="window.open(this.href);return false; ... Brix_Scale
A Caveat about the accuracy of the Specific Gravity Scale
Traditionally homebrewers used refractometers that only featured a Brix scale and converted to Specific Gravity by multiplying the Brix reading by four. The is fine at lower gravities up to around 1.040 but the higher your starting gravity goes, the less accurate the 4x conversion is. This same inaccuracy is found on the Specific Gravity scale on this refractometer, and every other model with a Specific Gravity scale that is available on the market today (July 2010). To get a 100% accurate reading you can plug your Brix Scale Reading into our free online spreadsheet, Promash, or a similar software to convert from Brix to Specific Gravity. If you are interested in more beer geekdom you can read more about this at the very end of the product description.

With that said we would still choose this model over a traditional Brix only refractometer because the distortion is relatively small and it sure is nice to have the instant Specific Gravity readings during the brewing process.
When I asked Northern Brewer about this they said they were getting a new batch of refractometers made with a corrected scale, ie non-linear

Knowing this, I bought a cheap chinese refractometer off ebay, but mine doesn't have the SG scale, but what it does have is an LED backlight :)) and from what I can tell, its actually better using the LED, than using a normal light source. I haven't used the refractometer in a brew day yet, but I expect the brix reading will be fine

Like this one
Image
Last edited by stux on 12 May 2011, 16:00, edited 5 times in total.
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III

5/7/12

Post #6 made 14 years ago
by Brewer Pete
I have always recommended the Brix refractometers from China and never use the ones with SG scales but being lazy sods I can see why others give them a go.

Once you understand the tool you can appreciate it better and use it like a pro, not taking the time to learn you would think it was rubbish. The following link will teach you:

http://www.aussiehomebrewer.com/forum/i ... t&p=445730

The next two will add a bit more knowledge and calibration technique:

http://www.aussiehomebrewer.com/forum/i ... t&p=445741

http://www.aussiehomebrewer.com/forum/i ... t&p=633870

The last will show measuring the ethanol light-bending skew during active fermentation:

http://www.aussiehomebrewer.com/forum/i ... t&p=459179

Cheers,
Brewer Pete
Last edited by Brewer Pete on 13 May 2011, 06:59, edited 5 times in total.

Post #7 made 14 years ago
by ianh
As I only brew beers with an OG of less than 1.060 I bought one of these 0 - 18% Brix refractometers

http://www.ebay.com.au/itm/Brix-Refract ... 35b1fe06fa

If brewing stronger beers then go the 0 - 32% Brix version.

I use it for both before and after fermentation SG's using a formula to correct for alcohol. Get good agreement between refractometer and hydrometer.

Broke my hydrometer recently (had it 40 years) won't be replacing it.
Last edited by ianh on 19 May 2011, 13:42, edited 5 times in total.
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