Paging PigletJohn, help me get this tap shroud off please

[PurpleToeNail]

As the title, I need to change or delimescale the ceramic cartridges in this kitchen mixer tap. The cold shroud comes off easily. The hot one won't budge, it's like it's super-glued in place. I've tried using a rubber glove wound tightly. I've tried using a G-clamp (because it has no teeth). I'm worried that using something with a big jaw will 'bite' the metal & ruin the look. I've also put an old screwdriver just inside the hole at an angle & given the shroud a little tap all the way round to see if that would loosen it. Nothing's working. Anyone have any clever ideas? (and yes that's the cold in the pic). Many thanks!
@PigletJohn

Omg! I did it. Time out for a coffee & it decided to give up fighting me.. . Let's see if I can get the cartridge out now...

You clearly found your inner PigletJohn - well done!

Sadly I have to give up. I cannot shift the cartridges at all. I even opened the kitchen window to lean in & pull rather than push the wrench to shift the nut. I reckon they were over-tightened. I can't move the cold either & that has no limescale. It's annoying because I rather like empowering myself to do these things.

In my experience, it's easier to buy a new tap than to try and take it apart only to find out that you can only access one side and it's inevitably the other side that's the bloody issue. (Which you only find out after fixing one side and putting it all back together)

Rubber strap wrench

May be listed as a "boa" or possibly an anaconda

The cartridge needs a ring spanner

Use the boa to balance the spanner so you do not rotate the tap in its hole.

And try pouring boiling water over it, the heat may loosen it.

not on a porcelain sink as it will crack.

Update! I had success, though I'm hoping you can come back @PigletJohn & answer a couple of further questions that might help myself & others.

I managed to get better leverage on the cartridge nut by using a longer wrench & wedging a few bits of wood behind the tap against the wall, to stop it twisting whilst undoing. Result. I watched a Youtube on cartridges to take it apart very carefully. There was a small amount of limescale inside but I think the washer was the main problem. I had both '16 & '32 washers, neither was correct. I attach a pic. On the left is the original washer & the centre & right were new. Can you tell us a bit about washers PigletJohn please. There's barely any difference but one is too big & one too small (in depth). I solved the problem by reversing the original washer, but this will only work for a while I imagine. I need to find the correct replacement.

Secondly, in the other pic, you can see the 'window' of the cartridge. It doesn't close completely. There is a tiny gap at each edge. Do you know why this is Piglet? Many thanks

For reference, that cartridge pic is using the '32 washer which was too big.

Love this thread ❤️

Those aren't washers, they're "O" rings.

You have ceramic cartridges in your taps, which are quite fashionable but wear out quickly and are expensive. The opposite in every way to tap washers.

The "O" rings are to seal the cartridge into the tap body and prevent it leaking round the thread. You can try lubricating them with plumbers white silicone grease, and winding PTFE tape round the Male threads. If you overlap it onto the shoulders it will probably prevent leakage and will also prevent the thread seizing again. After winding it, press on it with the pads of your fingers and rotate it to press the tape into the grooves of the threads. It is so thin that it will not block the cartridge when you screw it in. Rolls are very cheap. It prevents leaks by being unwettable so surface tension prevents water going through the gap (I think)

I expect your cartridge is worn out and the tap was dripping out of the spout. Is that the fault you were trying to fix?

Useful thread, thank you