[Hallicrafters] Alligatoring

[Carl]

Anyone who doesnt pay attention to the various materials used has seen this 
when restoring a vintage vehicle. Its also seen on the siding of older 
homes.

Carl
KM1H

----- Original Message ----- 
From: "TC Dailey" <daileyservices at qwest.net>
To: <HallicraftersRadios at yahoogroups.com>
Cc: <hallicrafters at mailman.qth.net>
Sent: Thursday, September 17, 2009 12:27 PM
Subject: [Hallicrafters] Alligatoring


>I stumbled across this in a copy of "Boatswain's Mate 1 & C"  (US Navy pub) 
>that I have here.  (I was a Radioman, but enjoy the texts).  It references 
>"alligatoring" in the section on painting, which is a very important part 
>of ship's maintenance.  It hit home, on how it was most likely done, or at 
>least how it occurs:
>
> ALLIGATORING
>
> Alligatoring and checking of a pain film exists when the outer layer of 
> paint cracks and presents a pattern similar to alligator leather.  This 
> condition occurs when relatively hard finishing coats are applied over 
> relatively soft priming or underlying coats.  Under coats which are too 
> rich in oil, or which have been allowed insufficient drying time, cause 
> this softness.  Expansion and contraction of the painted surface, where 
> paint coats have this unequal flexibility, causes alligatoring and 
> checking.  To avoid this failure, allow under coats to dry sufficiently 
> hard before applying the next coat.  Under coat materials should dry 
> harder than top coat materials.  Do not add too much oil to priming 
> materials.  To remedy this condition, scrape and wirebrush to remove loose 
> scale, sand to smoothness, and repaint.
>
> Tom - former USN
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