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Should the nuts and bolts be cleaned before using threadlocker MM115?

Permabond MM115 tolerates some oil on the nuts and bolts.  In most cases Permabond MM115 can be used on ‘as received’ nuts and bolts, but we recommend testing to be sure – particularly if nuts and bolts appear to be heavily contaminated.

A couple of points to consider:

  • Metal ions are needed for the MM115 threadlocker to cure, too much contamination on the components can reduce the amount of metal ions in contact with the threadlocker causing the adhesive to cure more slowly and hinder the strength development.
  • Threadlockers work by filling the microscopic voids in the metal surface providing better surface to surface contact, stress distribution and protection against moisture ingress, if these gaps are filled with oil and grease then the adhesive can’t get in, this affects final performance.

If you always clean and degrease nuts and bolts before using MM115 you can be confident in achieving consistent bonding and sealing performance every time. If surface preparation is not feasible in your assembly environment and components are particularly contaminated, you may wish to consider a more oil-tolerant threadlocking compound which will cut through grease more effectively. Permabond offers HM129 for this situation but again it is recommended to test for your own requirements.

If you do decide that you wish to clean components before bonding, a suitable degreaser would be acetone or isopropanol. Alternatively Permabond ASC10 activator can also be used as a cleaning agent on nuts and bolts, as well as speed up adhesive cure.

Surface preparation is a topic that is addressed extensively in our iPhone / Android app.  Go to to download the app.