The best way is to kosher them through 诇讬讘讜谉 讘讗砖. If not possible then put it in a pot with boiling water like you kasher your bechers. Better then all that is to buy new ones.
Realy i think that before 注讘讚讬诐 讛讬讬谞讜 the mask should be put on 讝讻专 诇注讘讚讜转, then by 讜讛讬讗 砖注诪讚讛 take it off 讝讻专 诇讞讬专讜转 and so on…..