Refractometer Use Tips

I bought an ATC 0-32 brix refractometer last month off ebay, calibrated it and used it for my last brew, a centennial blonde ale.

I watched Bobby M's tutorial and it was a great help. I had a few questions:

I was under the impression that a refractometer would be useful during my mash recirculation (I have a RIMS) to check how close I am to reaching my OG....I took a reading and it was way off, most likely because of the concentrated sugars (hadnt sparged yet)....am I wrong or how do I get an accurate reading pre sparge/pre boil to know if more mash time is needed and conversion is done...or is this possible?

Does anyone have any tips on how they utilize their refractometer?

Thanks for the help!
Joe

I think it would be difficult to get a reading from the mash because of the inconsistency in the samples. The way I utilize this tool is taking a reading after wort collection prior to hop additions. I do this for two reasons.
1. Confirm my mash efficiency
2. Calculate my original gravity after boil off
3. If my efficiency was way less or more than planned for, I can adjust my hop schedule

mark
www.backyardbrewer.blogspot.com
www.thebackyardbrewer.com

Are you correcting for temperature (I am assuming that your mash is ~150F as opposed to where the refractometer is likely calibrated closer to 75F)?

Have a read here: http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency

Your pre-sparge reading was not "way off." It SHOULD be significantly higher than the expected OG into the fermenter.

Additionally, a refractometer reading is not an accurate gauge of conversion. Do a starch test for that. Read here: http://braukaiser.com/wiki/index.php?title=Starch_Test

I have the same refractometer and my measurements were off compared to my hydrometer. I recalibrated the refractometer with deionized water and it has dead on since. Zeroing the refractometer with the right water will make a difference. You can use distilled water with good results. I also agree with mbird that you will get an inconsistancy in samples pre sparge. I use mine post sparge before hop addition.

Can you help me understand how why you take a OG reading before hop additions....and if you are not at your OG target, how do you adjust to hit the OG....add DME or???

Thank you

To combat inconsistent readings from the mash, I take my samples during the vorlauf.

Part of the reason I take readings throughout the process is to help me understand where I'm losing efficiency. I don't necessarily do anything to prevent those losses, I just try to keep things consistent from brew to brew. If something changes, I try to find the reason for it. Please read the website I linked. It should help immensely in understanding efficiency.

If I get a significantly lower reading than expected before the sparge (more than 1° Plato), I may sparge less and accept a lower volume into the kettle in order to keep the wort close to the intended strength. Monitoring the wort's strength every 15 minutes during the sparge will help determine when to stop. Alternately, for a dark beer, I may continue sparging as normal, but boil the wort for a longer period of time in order to concentrate it a bit. In that case, knowing the boil off rate for my system helps me determine the proper amount of time to add to the boil.

Awesome...thank you!