I would not use it if it is blue. We do not know what the blue is and it may cause damage. Try the hardware store for pure isopropyl alcohol (sometimes sold under the name of 2-Propanol). Also for removing drying marks I have just used a Q-tip or small paint brush dipped in distilled water. It does the job and only takes a short while to dry as it in only a spot and hot the whole negative that is wet.