Neonpower2 months ago000Does it have an expiry date or is that just theory? My spray is 10 years old and it does. But it can't harm the glass, especially coated filters, can it?Show in original language (German)stefanklinger2 months ago • purchased this product+110purchased this product Helpful answerI don't know that. However, since we are talking about chemicals (diluted ones), I assume that it doesn't do any harm - but I don't know. Show in original language (German)Comment