Obfuscation proofing - Am I doing this right?

[Foreshot]

Filled a flask with 500ml of spirit

Distilled to over 100c

Added RO water until it is back to 500ml

Measure Proof

Yes?

Cause if so then I magically made nearly double the alcohol than what I put in.

[JailBreak]

What was the estimated proof vs actual proof? Are you using volumetric flasks? Are the temperatures pre- and post-distillation measured as equal (or better yet match the volumetric flask calibration?)

[Foreshot]

Estimated: low 30s

I did not use volumetric flasks. I used graduated cylinders for measuring. I do have volumetric flasks. 

Temps were not the same. I did not record the first temp but I did for the second. I recorded 95.8p @ 76.5f - Hoochware says true proof of 88.8p

Base spirit: 51kg @ 86.4p, then added 22.95kg of 50/50 by weight simple syrup. 

 

One big note: So I didn't mix the spirit before I removed the sample. It looks like all the sugar stratified and there was more alcohol at the top based on tasting. I will redo my proofing later.  

[JailBreak]

I've learned through experience that the lab distillation for determining true proof requires a lot of attention to detail and one little mistake can ruin the whole thing and waste a few hours of work. I'd honestly follow the TTB's videos to the letter when it comes to this technique. 

Here's the video from the TTB. I don't have a water bath so I'll often use a fridge to get my sample close to the calibrated temperature on the volumetric flask both before and after distillation. The most important part is that the temperature before and after matches as well as the volume.

[Still_Holler]

I have been reading back through this  section because I broke my lab still the other day and am looking at evaporation method until my new one comes.  I had been under the impression Evaporation Method was only for spirits containing 400-600mg/100ml of solids and Distillation Method was for any amount of solids, but after rereading the below if seems that all these methods are for spirits in the range of 400-600mg/100ml?  What about spirits with more than 600mg?

§ 30.32 Determination of proof obscuration.

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(a) General. Proof obscuration of spirits containing more than 400 but not more than 600 milligrams of solids per 100 milliliters shall be determined by one of the following methods. The evaporation method may be used only for spirits in the range of 80–100 degrees at gauge proof.

(b) Evaporation method. Evaporate the water and alcohol from a carefully measured 25 milliliter sample of spirits, dry the residue at 100 degrees centigrade for 30 minutes and then weigh the residue precisely. Multiply the weight of the residue by 4 to determine the weight of solids in 100 milliliters. The resulting weight per 100 milliliters multiplied by 4 will give the obscuration. Experience has shown that 0.1 gram (100 milligrams) of solids per 100 milliliters of spirits in the range of 80–100 degrees proof will obscure the true proof by 0.4 of one degree of proof. For example, if the weight of solids remaining after evaporation of 25 milliliters 0.125 gram, the amount of solids present in 100 milliliters of the spirits is 0.50 gram (4 times 0.125). The obscuration is 4 times 0.50, which is two degrees of proof. This value added to the temperature corrected hydrometer reading will give the true proof.

(c) Distillation method. Determine the apparent proof and temperature of the sample of spirits and then distill a carefully measured sample in a small laboratory still, and collect a quantity of the distillate, 1 or 2 milliliters less than the original sample. The distillate is adjusted to the original temperature and restored to the original volume by addition of distilled water. The proof of the restored distillate is then determined by use of a precision hydrometer and thermometer in accordance with the provisions of §13.23 to the nearest 0.1 degree of proof. The difference between the proof so determined and the apparent proof of the undistilled sample is the obscuration; or

(d) Pycnometer method. Determine the specific gravity of the undistilled sample, distill and restore the samples as provided in paragraph (c) of this section and determine the specific gravity of the restored distillate by means of a pycnometer. The specific gravities so obtained will be converted to degrees of proof by interpolation of Table 6 to the nearest 0.1 degree of proof. The difference in proof so obtained is the obscuration.

[meerkat]

For spirits over 600 mg/100 ml use 30.31 (C)(1)

If the evaporation method indicates more than 600 mg/100 ml then you can estimate the true proof from the apparent proof using the Liqueur Hydrometer Temperature Correction calculator in AlcoDens LQ.  This is obviously not TTB approved but gives values that you can use in blending calculations.  The final product proof will have to be verified once you replace the lab still.

[Still_Holler]

1 hour ago, meerkat said:

For spirits over 600 mg/100 ml use 30.31 (C)(1)

If the evaporation method indicates more than 600 mg/100 ml then you can estimate the true proof from the apparent proof using the Liqueur Hydrometer Temperature Correction calculator in AlcoDens LQ.  This is obviously not TTB approved but gives values that you can use in blending calculations.  The final product proof will have to be verified once you replace the lab still.

Thanks, right in front of me but I somehow was reading past it.