"Spurtle" wrote in message
...
Andrew Mawson wrote:

I think it is no more than getting them ABSOLUTELY clean and hot
dipping in molten tin. Certainly this is how bearing caps are
done.
The problem is the cleaning to chemically clean bare metal -
possibly
you could sand blast them ?

AWEM

Thanks AWEM
Would have to be chem clean as they have a small rolled edge that
would
be difficult to blast clean in the crevice where it meets the mould
side. I have tried cleaning in a strong caustic solution and
achieved
visible removal of carbon, grease etc. Is that sufficient?

No flux?
Would the item be dipped cold, or preheated?
As it is for food contact, does it require pure tin?

Appreciate your help.

Cheers
Spurtle

Your problem is keeping the items clean between blasting / acid dip /
caustic dip or whatever and the tin dipping, as probably they won't be
done either in the same room or the same time ! Fry's make (made? -
long ago since I used it!) a tinning flux that if sprayed onto the
cleaned metal would keep it clean.

If you have rolled joins that can trap moisture, you have another
problem when dipping - the moisture will form steam explosively when
dipped and splash tin everywhere.

As to the purity of the tin I don't know, but tin tends to be
associated in nature with lead and arsenic so I assume that their
percentages should be microscopic for your application !


AWEM