Pepper Spray? Blackie is no real threat......take a pot and pan !!!!! Make noise and he will stay clear of you !!!! Avoid Mom and cubs by staying out of areas where they feed...... don't intrude and you won't need spray at all. Read about bears before you hike...respect them and their domain and you will be just fine...... just don't feed the bears or leave food where they can see it or smell it. Camp "clean" ...... and hike in non-stealth mode. If they hear you they will stay clear of you.
The best sprays on the market are ONLY good to 20 feet MAXIMUM so you better have big cahoona's to stand and wait for them to get close.
Any wind at all and you can cut that distance in half.
Best bear "spray" is a shotgun with buckshot.
Oh, sorry. Where are you going? Baxter??
One thing I will tell you is to get a green stick about 3 to 4 feet long and at least one full inch in diameter. Use it as a walking stick and IF you see a bear (I have seen three in the wild while hiking the last 30 years) make yourself as big and noisey as you can.
NEVER RUN AWAY, always move while FACING the bear. Use the stick if the bear persists but I don't think you have anything to worry about in Maine!