J2: Lamination Inlay Difficulties

Today I attempted to sweat solder my top sheet of 26ga copper(shape already pierced out)to my 20ga brass base. I laid it on the stand and wire mesh and heated it with a large flame from below. I stood there heating for about 25 minutes with no results. I tried just heating one corner, knowing that the sheet was too large to solder all at once. No luck with that. I am going to attempt double-fisting some torches with a large flame below and a small flame above. The piece is just too large for its own good.