No no no!
An amalgam is an alloy containing Hg having the interesting property of overvoltage. This means the Al wants to react and dissolve badly with alcohols and water producing H2 in the process, but this reaction is greatly hindered (NOT completely stopped, just slowed down a lot!) since H2 doesn't like to be produced on Hg surfaces.
When there is anything reducable around, like a nitro compound or an imine the Al can dissolve without having to produce H2 gas, and it readily will do so.
This reaction involves electron transfers between the reaction partners, which is just another way of saying the Al is dissolving and gives up its electrons to the Hg which in turn transfers them to the organic reactand to be reduced. It's not the Hg salt that breaks up the Al. If there is nothing around to be reduced then the Al can't get rid of those electrons, and it will not dissolve. Al/Hg in an inert solvent like hexane or toluene should be quite stable for a while. Al/hg will react with oxygen because Al is a very reactive metal which is only protected by its oxide coating (passivation), once that coating is removed it will oxidise in air, but that is usually not an option when covered by a solvent since O2 solubility is very low.
The solvolysis reaction with an alcohol will be very slow with thick Al because it has a much higher Hg loading on its surface and a much lower exposed surface area than foil.
Al/Hg in a pure alcohol: only very slow dissolving via solvolysis. Greatly enhanced by water presence (since Al2O3 formation is very exothermic and the driving force) and change to basic pH
Al/Hg in water: exothermic, will heat up considerably and might eventually react violently
Al/hg with nitro in alcohol: very exothermic reaction due to water formation, and since nitro is hot stuff
Al/Hg with nitro in alcohol containing considerable amounts of water and a base: let's not go there, runaway reaction with foil, very exothermic with sheet
Al/Hg with an imine in alcohol with a littlewater: rather slow and gentle reaction
Foil reacts much faster than sheet!
Don't try to tweak the reaction too much and reinvent the wheel! Al/hg works, in up to 90% according to the literature and some bees experience. And when done without haste and with thick Al it can even be very volume efficient.
I'm not fat just horizontally disproportionate.