[sandermarijn]

It may be that the instruction is wrong about splitting, and you should have mixed the whole liter at a time without measuring anything; or, it can be that the instruction and concentration is right and they put a wrong amount in the bottle.

That is exactly the problem, thanks for phrasing so concisely.

However, I have a "feeling" that the most general way for color chemicals is that the bottles have the actual, correct amount that, when mixed as instructed, will give right concentrations.

I think so too. Apart from the stab-bath, the chemicals in the larger 5 litre packaging should be exactly the same as those in my 1 litre kit. People must be splitting this 5 litre kit all the time, and apparently (from a lack of posts on the different forums) the splitting works fine.

I don't believe that Tetenal puts solvent in the bottles first and then adds the powdered active ingredients- I suppose this mixing happens in larger volumes at some earlier stage.

Then the lesser content of part 2 must be a filling mistake in the factory. Machines are only human after all

But again, can't know about Tetenal. Maybe you should ask them.

I thought of this but I figured that Tetenal will never admit to a filling mistake. I wouldn't if I were them. (Perhaps I'm being a bit too negative here.)

I could ask the people in the shop where I bought the kit (yes, a real brick & mortar shop!). I don't come there often and it's not very close (in relative terms), but if I do I will certainly ask. They are probably the only place in the country where you can still get these kits over the counter, and they should be quite knowledgeable on 'analogue issues'.

I have a suspicion that the shop will put it down to a filling mistake too.