while I feel it's regretful that rogerd feels that:
"web design isn't like creating a beautiful oil painting on a blank canvas."
I do agree with his statement that:
"I think teaching someone "artistic creativity" is difficult."
(altho I would suggest that he just hasn't yet been to the most visually stunning web sites, a la Joshua Davis or Brendon Dawes or hasn't seen enough crappy oil paintings yet!)
Artistic creativity is 5% talent, 95% desire. Improved creativity has to come from within. It comes from the personal desire to achieve a higher level of design capability.
Designers are only as good as they want to be. You can't make them improve by showing them examples or talking to them about improvement. Nor can you learn it out of books. In fact, showing them examples of the professional design you desire can have the opposite effect, dooming them to failure each time they fail to achieve to your expectations.
Improvement comes from investing countless hours practicing techniques. Improved creative capability takes time and can't be rushed. There are no shortcuts. It takes as long as it takes, and not a minute shorter.
In all likelihood, you don't have a thousand hours to wait. You need professional design now. Your business may depend on it. The most efficient way to get more professional design quality is to hire a designer who already possesses the skill level you need.
As for the junior designer in need of improvement? Two of the best ways to accelerate that improvement:
1. enroll your designer in a Photoshop class at the local community college for an entire quarter (usually 12 - 13 weeks long. Even if your designer claims to already know Photoshop. I've been using Photoshop for 10+ years and I probably only use half the available features. A web designer can never know too much Photoshop. The added benefit of class enrollment is improvement that comes from having to perform among peers. We are either under pressure to perform as well as others, or we are inspired by others to improve.
2. Hire a more senior contract designer who can mentor your junior designer for a few months while producing the level of professional design you need.
by giving your designer the tools to improve, you will find out soon enough whether your designer has the desire to improve. You will either get better work or discover you need to find another designer.
btw, I respect and admire your desire to give your designer an opportunity to improve. in the cutthroat design biz, most employers arbitrarily discard designers until they get one who produces what they want, without any regard to loyalty, temperament, ability to work with others or other positive attributes. "On the job" learning is a rarity anymore.
hope you achieve the desired results. best wishes.