Two things about hairspray....
BE SURE to get the MEGA-HOLD and ODORLESS variety....if you're determined to use the stuff. The odorless is really important....unless you don't mind having your layout have that lingering bouquet ofhair salon.
The other thing about hairspray...suggested above in Paul's response...is that it does not render the finished tree...or hair-do!...waterproof. C'mon, guys!.....think about it!! Would your wife/squeeze really put something on her hair to hold it in place that can't be washed out???? And, by the way, that includes HUMIDITY!!! Got a humid environment/basement??........you'll have green leaf drop, for sure! The 'Mega-hold' stuff gives a hair-do only a slightly better fighting chance in high humidity or a breezy day. But, unless you're in Las Vegas, Phoenix, or Death Valley....DRY climates....you'll be disappointed in the long run with hairspray coupled with ventilation breezes, and table-shaking from klutzy visitors to pounding Big Boys.
Diluted matte medium, Scenic Cement,.....acrylics.
But, TEHO, I say....
KD
...Daily Graduate of the School of Hard Knocks