I wouldnt blame your production technique, id be very suspicious of
the copper you used. All copper sheet is NOT the same!!.
To give you an example, Car/truck radiators made from copper up to
around the 1950’s/60’s used electrolytic grade copper.
These radiators do not corrode away like later made ones.
the reason the latter rot is that the grade of copper is made from
recycled scrap with other metals included.
This causes external electrolytic rot and these rads last about 7/8
So Id suspect the copper you used was not of the highest grade, ie
ASTM B.152-ETP called electrolytic tough pitch.
the best electrical grade you can get.
This is produced under special conditions that exclude oxygen.
Ive had another experience, electrical lightning conductor is made
from crap copper. Hot forge it and it cracks and crumbles away. The
best as above is never a problem.
Id get back to your copper supplier and ask for a refund, but check
what grade you asked for or specified.
Could have come from China.!!
Also, getting back to technique in making your laminate, I was under
the impression that between each layer you sprinkled silver brazing
particles to aid adhession along with a minute amount of flux to
exclude oxide formation. but ive never made this laminate so cant
Have you made this before and got the results you expected? In
discussions with the technicaldept of Johnson Mattey many yrs ago
over the production of a double’ l needed for an enamelling
This was 10% fine gold and 90% fine silver with a finished thickness
of 10/1000 in.
They always solder the 2 metals together to ensure a proper
molecular bond before rolling down to size.