What's a better heat-sink... brass or copper?

[DoctorCheney223]

I am going to reweld another MG42 and a Ultimax and was wondering which of the two is a better heat sink and backing for welding, brass plate or copper plate?

thanks,
Ron

[bolex]

Copper has the better thermal conductivity and therefore will draw the head away better.

FYI:

Copper 226 (high) 112 (low)
Brass 135 (high) 15 (low)
Units are Btu*ft/hr *ft^2 *degree F

[Pirate]

brass has zinc in it and is not good

[tony]

Anyone ever use the heat sink putty you can buy from Eastwood or other welding suppliers? Use it, and the copper backer plate and that should work great.

[MGMike]

I've got a can of the Cold Shield and some of their copper back-up strips that I'm planning to use. On my BREN weld, I'm also thinking about mashing some copper tube into the internal grooves to cut down on the clean-up inside

MikeD