PU Topcoat for Helmet is Soft

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Anonymous Poster	PU Topcoat for Helmet is Soft 05/19/2006 8:25 AM
	Nguyen Minh Son writes: We use product Auto Clear Plus HS (a kind of PU varnish) of Akzonobel for coating on the shell of helmet (shell made from fiber glass). We mixed varnish and hardener in accordance with ratio that the manufacturer recommended. After spraying the varnish and flash-off 30 minutes, we put the shell in the oven at 60 degree C in 6 hours. Then we assembled components of the helmet and packed it inside a fabric bag. The inside of fabric bag is velvet which is made from polyester. After packing for 8-10hrs, on the surface of varnish appears some traces of fabrics of the packing bag. Temperature of our factory is about 32-34 degree C. Does anyone know why this would happen? And is there a solution for this problem? Thank you very much.
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Anonymous Hero Guru Join Date: May 2006 Location: The 'Space Coast', USA Posts: 11119 Good Answers: 918	#1 Contact the paint manufacture 05/19/2006 9:09 AM
	They can tell you best practices and see if you are doing something wrong.
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rcapper Guru Join Date: Dec 2005 Location: Etats Unis Posts: 1871 Good Answers: 45	#2 depends on what you mean by dry... 05/20/2006 3:36 AM
	I'm no expert but in my experience with paints and epoxies and such there's dry/cured and then there is really dry/cured. Perhaps you need to let them set out for 8-10 hours or longer before packing them. Possibly the coatings is "cured" but not really HARD? __________________ The hardest thing to overcome, is not knowing that you don't know.
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Anonymous Hero Guru Join Date: May 2006 Location: The 'Space Coast', USA Posts: 11119 Good Answers: 918	#3 In reply to #2 Re:depends on what you mean by dry... 05/20/2006 7:58 AM
	You probably are right. Check the paint manufacture's process recommendations. I would bet there is a cure stage that you must go through and a post-cure stage. I know with some heat settable epoxies you cure at one temperature for a period of time and then a post-cure is done at another temperature that is slightly higher.
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dadw5boys Guru Join Date: Feb 2006 Location: Piney Flats, Tennessee Posts: 1740 Good Answers: 23	#4 soft top coat 07/31/2006 11:15 PM
	Check you product storage and the age of the coatings. Some coatings will not dry if they have ever frozen in storage or in transit. __________________ If you never do anything you never have problems.
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