She springs up and crosses to it, and removes a whiskey bottle. She pours a half tumbler of whiskey and tosses it down. She carefully replaces the bottle and washes out the tumbler at the sink. (1.71)
Notice that drinking is essentially the first thing Blanche does in the Kowalski home…
BLANCHE …Now don’t get worried, your sister hasn’t turned into a drunkard, she’s just all shaken up and hot and tired and dirty! (1.91)
Stella seems to be the only person that Blanche doesn’t attempt to conceal her alcoholism from. Why?
BLANCHE No, one’s my limit. (1.111)
Blanche recognizes that her drinking threatens her reputation. This is why she tries to hide it all the time; it contradicts her Southern belle persona.
BLANCHE …I’ll show you shuperficial – Listen to me! My tongue is a little – thick! You boys are responsible for it. The show let out at eleven and we couldn’t come home on account of the poker game so we had to go somewhere and drink. I’m not accustomed to having more than one drink. Two is the limit – and three! [She laughs] Tonight I had three. (3.131)
At what point does it become clear to Mitch that Blanche is lying about her drinking habits?
The rapid feverish polka tune, the "Varsouviana," is heard. The music is in her mind; she is drinking to escape. (Stage Directions, Scene Nine)
This is a key stage direction from Williams because it lets us know WHY Blanche drinks the way that she does. Indeed, many of her actions and words have to do with escaping both her past and the harsh reality of her current situation.
BLANCHE [She rushes about frantically, hiding the bottle in a closet, crouching at the mirror and dabbing her face with cologne and powder.] (9.3)
Blanche tries to hide both her age and her drinking – two things that threaten her potential match with Mitch.
MITCH I told you already I don’t want none of his liquor and I mean it. You ought to lay off his liquor. He says you been lapping it up all summer like a wild-cat. (9.22)
This is meant to be insulting to Blanche because her alcohol consumption is incongruent with her stereotypical over-the-top femininity.
Blanche has been drinking fairly steadily since Mitch left. […] As the drinking and packing went on, a mood of hysterical exhilaration came into her and she has decked herself out in a somewhat soiled and crumpled white satin evening gown and a pair of scuffed silver slippers with brilliants set in their heels. (Stage Directions, Scene Ten)
Alcohol is fuel to the fire, as far as Blanche’s mental illness is concerned. She uses it to further delude herself.