Do you mean a slitting saw to go in a milling machine?
Abracs do .75 slitting discsThe thinnest you're gonna get in 4" is 1mm surely? Abracs are alright. Phoenix II.
Depending on the thickness better to cut thin aluminium with snips or thicker I always do on a guillotine. Never get a straight clean edge with a disc.
clean it with Acetone. It is the choice of places like Roll's Royce prior to welding as it evaporates leaving no trace
I believe it can induce the 'feel-good factor' if one breathes the fumes to too long......
I used to use it when replacing the grips on my golf clubs.
Not sure i would admit publically to owning golf clubs, they waste tool storage space