Ilford, now Harman, ship their chemicals in high quality bottles made to outlast humanity. Not so good though is the cardboard disc they have always used in the screw-top lid. This has always been a drag for things like photowash where the contents last for years but the lid goes soggy in weeks. It is a pity though not to reuse these high quality bottles just because the lids are rubbish. My easy answer is to buy plummers ‘O’-rings, which you can get in a perfect fit, cost next to nothing and last forever.
If you have got any simple tips please let me know!