Brewed this yesterday.
Finally settled for
For 20 liters of 1.060 OG kuyt:
4.5 kg malted oats
1 kg malted wheat
1 kg kg pale
β-glucanase rest at 40°C for 20', 3 l/kg.
Pulled about 12 liters of thick mash for a decoction. Brought that to a boil whilst stirring to prevent scorching.
Recombined with liquid mash which brought it nicely up to 65°C, where I kept it for another hour.
Batch sparge to collect 25 liters of ridiculously cloudy wort. Seriously, it looked like a clay suspension. Mash bed settled into a solid brick of grey despair.
All in all, lautering didn't go as badly as I'd feared, but this is one ugly mofo for sure.
As it came to the boil, a really big (I'm talking huge, as in almost an inch) head of hot break started to form. I skimmed most of it off, but more kept forming as the boil began in earnest. I reckon oats contain plenty of protein, plus I never started with clear wort anyway.
Added three handfulls of old Saaz @ T-60' (for preservative purposes)
Added 14g of dried wormwood in a hop sock @ T-30'. Was supposed to leave that in for the remainder of the
boil but after 10', its bitterness had become so prominent, I decided to pull it out.
Added 14g of dried yarrow, 14g of fresh rosemary and 20g of dried heather in another hop sock @T-15'. Rosemary smell was prominent, but wormwood still dominated the taste.
Dumped in fermenter and allowed to cool overnight.
Pitched with active starter of Fantome dregs this morning.
A wort sample I took at the end of the boil showed remarkable trub settling once it cooled. Roughly a third of my measuring cylinder ended up filled with greyish sludge, the top layer turned out to be serviceable hazy dirty-straw colour reminiscent of berliner weisses. Flavour was no longer dominated by wormwood, though it was still very present.
Will add gale in secondary once primary fermentation's done.
Fun brew, but not something I recommend except for the pathologically curious. I'm not sure how historically accurate the Koyt angle is, but I have a hard time imagining anyone would brew such a husk-less mess for a living, even in times of famine, illiteracy and the unexpectedness of the Spanish Inquisition.
Oat malts are lovely in every other way though. Luscious, velvet crackery goodness.
Gruit...I can only repeat the advice already given by Dave and just about everyone else who's ever used gruit herbs in beer: use less. Plan your brew, set a herb dose, then reduce that to no more than 20% of what you set out for. Then use about 1/10 of that. Seriously.
I sampled a wormwood tea a prior to brewing this. 1 gram steeped in 25 cl of hot water. Bitter as your ex. Diluted to 10%, it still attacked the tongue in that numbing wormwood manner. Thinking 14 grams in 25 liter of sweet wort would yield a palatable bitterness was a delusion. Use less. Be prepared to pull the wormwood as soon as you think the brew's had enough.
Yarrow...I'm pretty sure fresh yarrow flowers are infinitely preferrable to dried yarrow (which seems to comprise mostly leaves and stalks). Couldn't pick it up in the wort, but perhaps fermentation will have an impact. I hear yarrow in the dry-hops stage gives positive results.