[SEL] Cracked Head/Epoxy information

[Elden DuRand]

Jim:

Interesting stuff!

Take care - Elden
http://www.oldengine.org/members/durand 

> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com]On
>  Behalf Of Jim Hardman
> Sent: Saturday, January 24, 2009 04:10 PM
> To: The SEL email discussion list
> Subject: Re: [SEL] Cracked Head/Epoxy information
> 
> 
> Jerry, specify a "high peel strength" epoxy for 
> brass.  It doesn't cure as 
> hard as most epoxies, you can dent the stuff with 
> your fingernail.  But it 
> sticks like grim death.
> 
> The secret with brass is surface preparation (as 
> rough as possible and as 
> clean as possible) and thick sections of brass to 
> prevent "stretching" off 
> the bond when stressed.
> 
> Epoxies bond well due to their ability to wet the 
> surface;  these chemicals 
> have the ability to gain really close molecular 
> contact.  But mechanical 
> roughness (rough grinding) truly helps mechanical 
> purchase.
> 
> With all epoxies, wash up well with plenty of 
> soap and hot water after use. 
> There are no "safety cures" that really avoid 
> possible skin rash.  Everyone 
> has a natural threshold resistance to dermatitis 
> (a rash like poison ivy), 
> but once the threshold is reached, the user 
> becomes sensitized and has to 
> avoid epoxies in the future.  It's like rolling 
> in poison ivy as a kid.  The 
> first or second time you got away with it, but 
> after that, just get near the 
> ivy patch and you had the rash.  Just be clean... 
> most of our shop mates 
> formulated epoxies for years with no ill effects.
> 
> Jim in Vermont