Not entirely true. A proper degreaser put on with one rag and wiped off with
a clean one BEFORE it dries is the proper way to remove surface
contaminants. Sometimes sanding alone merely grinds the contaminants into
the substrate, only to surface again later. Here's my procedure. First, wash
the parts with warm soapy water. Water will remove contaminants that solvent
based cleaners will not. Second, give the parts a good cleaning with a
solvent based cleaner. Third, give the bonding areas a good sanding with 30
to 100 grit paper. Fourth, give the areas to be bonded a last solvent
cleaning 1/2 hour before epoxying. (that's to let the solvents flash off)
And you will not have any bonding problems. It might seem like overkill but
it really isn't.
Jim Thursby
-----Original Message-----
Behalf Of Graham Singleton
Sent: Tuesday, March 09, 1999 7:02 PM
Subject: Re: Cleaning cured epoxy
>I am about to start making bonds to my cockpit module and have
>started considering how to clean off mold release compounds and
>dirt/grease before bonding. Would MEK work and not leave a residue?
There should be no mould release on the bonding faces of either cockpit
module or fuselage. In any case you are better using dry abrasive, solvent
just moves contaminants around. Always abrade the two surfaces to be
bonded, except when bonding metals. Chemical etch is best for this.
Boeing specify a test where distilled water is dropped onto the surface, it
should spread out completely. If it doesn't the surface is not clean.
Graham
-----Original Message-----
Behalf Of Graham Singleton
Sent: Tuesday, March 09, 1999 7:02 PM
Subject: Re: Cleaning cured epoxy
>I am about to start making bonds to my cockpit module and have
>started considering how to clean off mold release compounds and
>dirt/grease before bonding. Would MEK work and not leave a residue?
There should be no mould release on the bonding faces of either cockpit
module or fuselage. In any case you are better using dry abrasive, solvent
just moves contaminants around. Always abrade the two surfaces to be
bonded, except when bonding metals. Chemical etch is best for this.
Boeing specify a test where distilled water is dropped onto the surface, it
should spread out completely. If it doesn't the surface is not clean.
Graham
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