Hi Mike

 

Acetone won't harm the laminate at all.  The only way it would do anything is if there is uncured laminate and if that is the problem, you have a much bigger problem than acetone residue.  Some have noted that methylene chloride was once suggested for laminate prep.  That's fine but has a risk of cancer if inhaled.  But the real danger of that is really very low so I wouldn't feel at all scared of using it for momentary wiping exposure. 

 

I know it has been batted around a bit already but the ONLY thing these solvents are suppose to do is clean up any dust after grinding and get rid of any loose contaminates before grinding (like mold release).  An ideal preparation scenario is:

 

1.    If really dirty or concerned, scrub down the part with warm soap and water, rinse thoroughly and let dry.

 

2.    Wipe down the area with acetone, MEK or MeCl before grinding to get rid of any surface contaminates.

 

3.    Grind/abrade the surface with clean abrasive paper.  NOTE:   Some hard laminates of glass will dull the disks very quickly.  If you notice burnishing of the laminate, change disks immediately and try grinding with less pressure but higher RPM.  A grinder is NOT an appropriate tool for preping thin and cored laminates,  A DA (Dual Action) sander, orbital or by hand is better.  Note that coarser grits should not normally improve most bonds and can weaken the laminate so don't go overboard.

 

4.    Vacuum up the excess dust then wipe off acetone, MEK or MeCl and a clean paper towel or better yet lab wipes called Kimwipes (Kimberly-Clark).  These are non-abrasive, non-contaminating (very important) and lint free but also don't tear and pill under abrasion.  Ideally, this should be a damp wipe to get off major dust, then a wash with a wet wipe to clean deeply into the laminate to get rid of dust contamination.

 

NOTE:  for an ideal surface prep, you should use at least technical grade solvent.  All sovents contain impurities and the stuff you get at the hardware store has quite a bit of impurities.  What isn't wiped off, evaporates and leaves a residue between the laminate and adherend.  Technical grade is relatively expensive compared to industrial grade but you at least know what you are getting.  With industrial, you never know and a LOT of that stuff is recycled from solvent recovery systems in plants with who knows what impurities.  Yes, I do use a lot of industrial grade acetone for prepping but not on super critical parts.

 

This should be ready to go.  The choice as to which solvent is superior is moot since these solvents don't attack or loosen up any of the matrix resin or fibers.  And if you have removed surface contaminates before sanding, all that should be left is dust on the surface.  The solvent itself imparts no special surface foo foo. 

 

To summarize:  if you were to test 4 identical laminates prepped with 100% pure MEK, acetone, MeCl and some super vacuum and they all were cleaned to absolutely pristene condition (not achievable but this is an example), they would all have the same bond strength.  All the solvents are doing is cleaning the surface after grinding, nothing more, nothing less.  It in no way acts as a primer, softener (like TSP for paint), or anything else.

 

Dan