Steam iron

[WeatherwaxOn]

I don't iron unless I really have to.

Was trying to iron something today and every time I press the steam button little black crusty bits keep coming out onto the fabric. Unfortunately there have been a few dots of dirty water (despite iron being emptied out previously and just filled with clean, fresh water), and I now have to wash the top I was ironing again to get the marks off.
The black crusty bits themselves are dry and are not making any marks.

Any ideas what they could be, and how I stop it happening again?

Have you ever descaled your iron?

If by "descale" you mean 'largely ignore and leave hidden in the garage'....

No, I have no idea how to. I suspect you may have identified the problem.

Think you can buy descaler or use white vinegar.

OP I don't iron either. I find steam irons really only work if in constant use and descaled, so instead of that in the rare event I want to steam iron something I use a plant sprayer to dampen the item and then just use the iron without the steam. Works a treat and no fear of nasty old gunk coming out of a neglected iron.

@dementedpixie

Think you can buy descaler or use white vinegar.

I've got white vinegar. So, tip out water, put in vinegar, leave a bit then blast through stream vents, I guess.

Bound to be something on YouTube

I have this same problem, and even with a brand new iron it started after a few weeks. I have a holiday let with white cotton bedding so I have learnt from experience it can be very annoying and time wasting to get any dirty drips on my duvet covers and have to rewash them. I descaled my iron using a descaling sachet and from now on I am only using deionised water (the type you get from car accessory shops) but I have to test it on a tea towel first to make sure it’s ok to use the steam function. I usually use a spray bottle to dampen the fabric but then the linens need airing before folding as they’re a bit damp.

I looked up the instructions for how to clean it, and followed them. It's still spitting out crusty bits.
Have now filled with white vinegar and a lot of muck has come out. I'll give it another vinegar treatment, then flush through.
I don't iron much, so a bit reluctant to fork out on special water for it!