Stock Solutions

  • 100% Anhydrous Ethanol (EtOH)
  • 100% Anhydrous Methanol (MeOH)
  • Na methoxide (Sigma-Aldrich) or aged Na ethoxide:
    • Aged Na ethoxide: Place ( 1 inch of NaOH pellets in a heavy glass 500-1000 ml bottle with a glass stopper covered in Parafilm. Cover the pellets with ( 3 inches of EtOH, seal and place in the hood. Shake daily until the solution becomes dark brown and syrupy (7-14 d), whence it is ready for use. Add replacement EtOH as the stock is used. Mark as an extremely hazardous, caustic reagent.
    • Na Methoxide: 50:50 Na methoxide and MeOH. Mark as an extremely hazardous, caustic reagent.


  1. Working solution: Dilute stock Na methoxide/ethoxide 1:4 v/v in anhydrous EtOH. It is critical that all solutions be absolutely anhydrous. If you doubt the 100% EtOH, don't use it.
  2. Place slides into glass or steel carriers (not plastic) and immerse in the working solution. The general etching time is 14 min/micron and is linear (e.g. 30 min for 2 microns, 7 min for 500 nm, 1 min for gold 90 nm sections). Note that the working solution can be used for several days if kept anhydrous.
  3. Drain the excess solution by blotting the carrier onto a stack of paper towels.
  4. Immediately immerse in 100% EtOH or MeOH and wash 2 min. Repeat 3X with fresh alcohols.
  5. Rinse slides 5 min in running cool tap water
  6. Dip slides in dH2O and air dry.
Disclaimer: As conditions of use are outside our control, Signature Immunologics makes no warranties, express or implied, and assumes no liability in connection with use of this protocol.

© 2000 Signature Immunologics, Inc.
Copying and distribution: This Technical Note may be copied and distributed for educational and non-profit purposes as long as acknowledgement of Signature Immunologics' copyright is included in every instance of use. It may not be sold or distributed for commercial gain.