The drink called Paintstripper has an ingredient something neat.
You can not fix the drink in the first act.
Read other parts of the instructions. Especially the glossary.
Neat means plain alcohol, with no additions.
Isn't drinking alcohol at the office a noir clichè?
Every private investigator has whiskey in their office desk drawer.
In your office. Open the desk drawer and use the hideous mug on the brandy decanter.