"Shaking Like Mad" is most assurable adding in a whole lot of potential Oxygen. Combine that with even a bit of iron in the tap water and yeah, you'd get thin negs. Mix it again that way and you'll probably get thin negs again.
Stirring fairly vigorously with an small paddle *without making too many bubbles* its the best way, not too hot. Oh and try distilled or carbon filtered next time.
I use Tmax quite a bit, when i want 'smooth' sharp pictures, usually i use D76 1+1 for that. Other films i use are agfa APX 100 which i have loads of, and ilford FP4+ in D76 1+1 or rodinal if i fancy grit. and HP5 pushed to 800 in D76 1+1 for atmospheric, grainy but pleasant portraits.
I used to use TMZ alot but as i always shot it at 1600 I now use TMY as TMZ was discontinued but there seems to be loads of stock for when i want the extra shadow detail.
Never knew XTOL was so sensitive to oxygen, as i have mixed my own ascorbate developers before. Unless it is to do with the phenidone, but i have used plenty of them before too.
I do still have the packets, the exp. date was 2015-11 so well within date, 12 - 11 - 207 was the number above that.
I mixed it at 20C if that makes a difference, i assumed hot water would cause damage.
My main reason for switching to XTOL was to do my bit for the environment, but i really do need reliability, which D76 and ID11 have both proved themselves to me as being very robust; as i shoot personal and family moments on film and many of which are not repeatable. These test rolls were unprintable, but might just be scannable. But as i am all analog failure is not an option. I had D76 go on me once, but that was user error it was an air leak in the bottle i had used, but luckily them negs (christmas, one of which was a portrait that has since been blown up to 12x16) were printable and gave a lovely, low contrast, gritty atmospheric portrait that i was able to replicate by reducing the time 25%, so that worked out in my favour in the end as it produced a lovely portrait and i have used the technique a few time since. (it was ilford HP5, at 800). I usually run clip tests first... The black where the leader is is not completely black on these tests, it is opaque (somewhat) but is much less dense than it should be.
Xtol is far from "so sensitive" to Oxygen, but not following the mixing directions on the label you shouldn't be too surprised that you got thin negs. Mixing with regular tap water at 20C and pouring the whole bag into a jug and shaking it 'like mad' until dissolved is just plain Wrong and Incorrect. BAD. Don't do it again. If you want to use Xtol learn how to mix it, its not D-76 or Rodinal, there is lots of proper guidance on APUG.
I've used Xtol for more than 10 years, for unrepeatable wedding photography so I value highly consistency and reliability.
I mixed the second batch with distilled water, and used that to dilute 1+1, let it sit for 30 minutes before using. Test strip came out perfect with boosted contrast as to be expected from increasing the times. Used tap water to mix 1+1 as an experiment, let it sit for 30 minutes and then tried it. Thin negatives from a second test were the result. Not as thin as the botched ones but the sprocket numbers were thinner than they should be, as were the images. I used the same time as i had for the botched rolls for both these tests. I always do a test before anything mission critical anyway, so all that got lost was developer and a couple of test rolls, not anything crucial! A bummer at £10 a packet but hard lesson learned. I tested with filtered water, that test strip came out fine as well. I wonder what it is in the tap water that harmed XTOL but has allowed me to use C41, E6, RA4 and many other film developers without a problem. The test negatives from the under developed ones were printable, and the first ones printed nicely as well, it seems a bit sharper than D76 at 1+1 or is it just my eyes? I mixed this batch more gently as well. I will be mixing all chemicals from filtered or distilled water from this point.
I have always been quite vigorous in stirring chemicals as well,
thanks for the advice though guys, never had a failure of developer in this way before!
Its probably some Iron somewhere along your water line. Filtering cuts that down. Look into how Replenishing Xtol fits into your processing, that's becoming a preferred way to use Xtol.
An update guys... After using a few rolls (developer worked well, as it should after the problem was sorted), i prefer D76 / ID11 1+1 and 1+3, but if i want 'fine grain' as in more solvent, XTOL stock seems to be 'sharper' than the D76 and preferable in a situation where i would use stock. However I do prefer 1+1 for most things, so i am back to ID11/D76 for general purpose, but will always keep some XTOL on hand. If i want pin sharpness and nice texture to an image, rodinal is my developer of choice. FP4+ in rodinal is lovely (35mm), as is PAN 100, PAN 100 gives such an old, grainy, unsharp kind of look, but it really is nice! XTOL was just lacking the 'pop' for me, the negatives seemed a bit more flat, temperature was maintained as well, i maintain it for B/W at 20C as i do 38C for colour.
So XTOL... i have tried it but prefer D76/ID11 : - )
Thanks again for your help on this topic guys!
I'm very glad you found a solution to your problems.
For what it's worth, I think the Xtol packets instruct to mix the developer in 80-90*Fahrenheit water, and stirring. While it's unlikely to have affected your results to mix as you do, (given your success with filtered/distilled water), it might be wise to follow the manufacturer's recommendations instead.