Yuk.
I think it might be time to clean the iron, and fit the new ironing board cover.
This is what happens when you use a lot of synthetic fabrics and iron-on interfacing. Things melt and stick, and you’re left with a mess.
That’s why I usually buy the cheapest iron I can possibly find, and then use it until it’s either beyond cleaning, or the heating element burns out. Domestic irons aren’t designed to be used for hours and days at a time, so this tends to work out to a buying a new one every eighteen months or so.
I know that a lot of dressmakers swear by heavy-duty steam-generating irons. I’ve used them before, but find them too heavy for my bad wrist. I also find that the water tanks get full of limescale and the steam eventually leaves dirty marks on your fabric. I use a simple plant sprayer, using it to dampen either the fabric, the ironing board cover, or a separate pressing cloth. A nice hot iron on top creates plenty of steam.
When I (eventually) finish work on my current costume project and switch to my lovely organic cottons, I’d like to give up using iron-on interfacing altogether. Hopefully that should help my irons to last a bit longer – and make a lot less mess!