TechNet,
     In a past life, while dealing with expensive Mil
     boards, I have removed epoxy based masks using heat
     and a sharp, flat wooden spatula.
     
     The trick here is to closely control the amount of heat
     applied to the board. With practice and experience
     you can raise the temperature of the board to above
     the Tg of the mask but below the Tg of the butter coat
     and carefully scrape the mask off the board, working with 
     small areas and not rushing the process.
     
     It does take patience and practice, there is risk of damage
     to the board, but it can be done.
     
     The views expressed here are not necessarily those of my 
     employer.
     
     Lyn R. Lynch
     Coates ASI
     
     

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