Dear Sir. Concerning your issue about the acid used to wash filter glass. Can be washed with soaking in a 10% HCl solution until ready for use. This should prevent clogging by any potential organic film. Make sure its rinsed well in DI before use. I think the following below links may help you in your issue:

http://unicorn.ps.uci.edu/M3LC/handouts/CleaningPyrexGlassware.pdf

http://www.fenzi-na.com/pdfs/PPG%20Glass%20Washing%20Technical%20Bulletin.pdf

http://www.robuglas.com/en/service/cleaning.html

Thanks

3/24/21

Dear Jubyeong,

Phosphoric acid is OK. You should never use HNO3 for cleaning purposes, as it can react with organic compounds in dirty glassware and form a nitrated product that can explode. Stay safe!

I hope this information helps you.

Bill Colonna Ames, Iowa, USA [email protected]

Common laboratory borosilicate glassware ─ often either called 'borosilicate 3.3' or Pyrex® glass ─ is expected to be seriously corroded by concentrated (conc.) aqueous solutions of phosphoric acid above ~120 °C. Use of conc. H3PO4 (> 30 wt%) from ~40 ºC to ~120 ºC is also not recommended, in general, but can be found acceptable after carefully consideration of the particular experimental circumstances involved by experienced users. Below ~40 ºC, corrosion is expected to be small, but prolonged contact of the glassware with conc. H3PO4 should be also avoided, particularly when volumetric glassware is used or when contamination of the contained liquid with ions contributed by glass corrosion must be avoided to any appreciable extent. Besides these generic guidelines, it would be also advisable to refer to the technical literature that may be found issued by the glassware supplier.