Does a blackjack dealear hit on18?

No. Blackjack dealers ALWAYS stay on 18 or higher and ALWAYS hit on 16 or lower.

So what about 17? Dealers ALWAYS stay on a "hard 17," which is a 7 and any card worth 10. A "soft 17" is a 6 and an Ace (counted as either a 1 or 11) and can therefore be considered a total of 7 or 17. Each individual casino has their own rule about a soft 17. The surface that the dealer deals on is called a "green," and the casino rule about a soft 17 is ALWAYS listed right there on the green. "Dealer hits soft 17" means just that, that he must consider the total to be 7 and hit. "Dealer stays on soft 17" means that dealer must consider the total to be 17 and stay, which gives you a slight advantage.