Re: Siemens HB904 – glass door cleaning
possibly look at something like this
https://dirtbusters.co.uk/products/view … aner-750ml
does not say it cant be used on glass (you could email and ask )
you may find you have to apply and leave it numerous times to get it off
with a bit of luck a non caustic product like this will soften it and then carefully with a decent scraper (you can buy ones that use a Stanley blade) you can scrape the worst off
alternatively pay to have the oven professionally cleaned then all you have to do is keep on top of it from there
Dave