First, let me thank you soooo much for your business. Our online customers and guests at our bar are the most important part of our operation. I can't express my appreciation enough.
Okay, a typical water extraction of fully saturated ground kava root will release approximately 50% of the kavalactones in that root (although more kneading and agitation may extract a bit more). For simplicity's sake let's say you are making kava with an amount of root containing 1,000 milligrams of kavalactones. The first squeeze will extract approximately 500 milligrams of kavalactones (1,000 x 50%). Re-soak and strain that same amount of kava which now contains 500 milligrams of kavalactones (1,000 - 500), and you will extract another liquid containing 250 milligrams of kavalactones (500 x 50%). You can keep doing this really an infinite amount of times but will obviously diminish your returns with every extraction.
Please note: I own a kava bar and strive to be the best kava vendor around. The info above is based on research I've done to put me in a place where I feel comfortable in this line of work. That being said, I am not a scientist and don't have the means or knowledge to put a bunch of samples through testing to 100% confirm this information. If anyone out there has other input, even if it contradicts mine, please share. I'm always learning and am happy to do so.
As far as larger quantities than 1 kg. go, the BKH website will allow you to order as much kava as you want, simply mark a number greater than 1 in the quantity box at checkout and Bob's your uncle, you will be quickly shipped the proper amount. We do offer kava wholesale as well though. If you are ever considering an order of 5 kg. or more shoot an email to the contact on the website and we'll get you a wholesale price.
As for your wife, man kava is fickle, it's just harder for some people to really get to that place. I personally wasn't noticeably affected by kava until at least the tenth time drinking. My advice is to first make sure she is drinking on an empty stomach. Have her drink in the evening as well. Give her a cup of hot tea (Ni-Vanuatu swear by this) after three shells or so, it doesn't matter what flavor though I prefer an herbal without caffeine. Have the lights relatively low and keep the noise down. If she doesn't soon feel it, simply ask her to pay better attention to how she sleeps that night. Even people who claim to not feel intoxicated from kava often report much better rest with very vivid dreams. Sometimes a night like that will help the drinker appreciate kava more which will lead to better future experiences.
Hope that helps.