How Much Lye To Use?

Here we are investigating the ideal amount of lye to use in dpTek1. Lye is necessary for the basifying but excess dissolved lye increases overall viscosity of the soup which is suspected to have adverse effects as detailed in conclusions 2. and 3. of the effect of salt page. It also may lead to the presence of trace amounts of unidentified goo in the finished Purity Flakes.

Conclusions So Far

From the tests performed so far it appears possible there is scope to reduce lye quantity, but only if the acidification stage can be guaranteed to be sufficiently thorough.
Currently, it appears prudent to stick to the current 110g of lye (if using 2L container) for dptek which will act as a safeguard against a sub-optimal acidification stage (i.e. low ambient temps of thaw stage, expedited or skipped freeze/thaws etc)

Test 3 Performed by Minty Love, Dec 2023

Comparing three otherwise identical batches, except 120g vs 60g vs 30g lye, approx 1.2 L of tap water

Notes:

The results show reduced yield for lower lye quantities. However if (as suspected) the acidification stage was adversely affected by the low ambient room temperature for the thaw stages, then it's possible that less lye could have been used in higher ambient temperature without loss of yield.
If acidification isn't complete (success of quick cool pulls rely on ATB mode and a complete acidification stage) then I surmise that a proportion of the flakes are extracted in STB mode, which might explain the overall low total yield of all three samples (1.2-1.3% would be expected from this bark batch), plus the higher-than-expected yield in the third pull.
In the light of these and F3Z's tests below, I don't believe we currently yet have sufficient evidence to lower the lye recommendation from it's current 110g.

110g of lye can be purchased for £0.48 - e.g. 5 kilos from ExpressChems for £21.99 (free shipping https://expresschems.co.uk/products/caustic-soda?variant=40799304646855 ) so the cost saving is negligible. But MHRB in a 100g extraction is worth over £10:00 (buying a kilo at a time).

There would appear to be no environmental concerns for lye disposal. Indeed according to wiki, it's actually used to raise the ph of drinking water, plus a huge variety of other uses throught the food and detergent industries https://en.wikipedia.org/wiki/Sodium_hydroxide

The only reason I can think of to reduce it in dptek is user safety. But again, this isn't an issue if proper precautions are followed, and they would still have to be even with reduced lye.

From the tests performed so far, my opinion is unchanged - make sure there's enough lye present, plus a bit extra. 100to 120g would still seem appropriate for a general recommendation.

Test 2 Performed by F3Z, Nov 2023

Comparing two otherwise identical batches except 60g vs 120g lye

Powdered MHRB Bark 100g ,
Distilled Water 1200ml + 250ml for 3rd & 4th pull
Salt 184g
White Vinegar (5%) 220ml
Naphtha 150ml + 100ml + 80ml + 60ml (reused naptha on 4th pull)

Using 120g lye

1st pull (20.2c) = 373mg (white light scrape) + 292mg (off white hard scrape)
2nd pull (20.0c) = 59mg + 254mg
3rd pull (19.8c) = 173mg yellow
Totals: 432mg White, 546mg off white & 173mg yellow

Total purity flakes 1.151g (1.1%)

Using 60g lye

1st pull (20.2c)= 286mg + 234mg
2nd pull (20.0c) = 117mg + 198mg
3rd pull (19.8c) = 171mg yellow
Totals: 403mg White, 432mg off white & 171mg yellow

Total purity flakes 1.006g (1%)

Notes

The first two pulls the solutions was very lightly shaken. On the 3rd and 4th pulls, around 250ml of distilled water was added to each bottle and shook the hell out of them.
With the 60g of lye a slight emulsion started to form for the 3rd and 4th pull
Overall quantity is consistent with the first extractions I did using Cybs hybrid tek. So the extraction percentage is on par for this batch of root bark I have. However the initial light scrapes definitely produced cleaner whiter crystals using the DPtek.

Test 1, performed by ML mid-2022