Re: Why does a polypropylene adhesive sublime?

	The types of hot melt adhesive that you are using are generally 
comprised of three major components; Polypropylene, acrylic acid (propenoic 
acid), and an organic peroxide.  The particular organic peroxide used is 
variable and is highly dependant upon the application that the adhesive 
will be used.
	Although I cannot be certain due to the unknown nature of the 
organic peroxide, What I think may be happening is that the nickel to which 
you are applying your hot melt adhesive may be acting as a hydrogenation 
catalyst.  In essence, one of the components of the adhesive is being 
converted by catalytic hydrogenation to a more volatile substance.  Since 
the properties of the component have now changed from what it was in the 
original adhesive and it can sublime out at room temperature.
	This explanation, however is only speculation since I don't know 
the exact composition of the adhesive.