Success with 4 iron at last

Hi Guys
              I was very pleased with my latest coaching session, we were working on "Low Irons" and he noticed I always avoid the 4 iron, after hitting a few balls, he said "so whats the matter with your 4 iron"  OHhhhhh!  Im hopeless with that  Simon I reply, now come on, try it was his reply, so after  2 vicious hooks he stopped me, "I can see what your doing" you are keeping the clubface slightly "too closed" halfway up your backswing, so after a few practice swings I apply the corrections and Wow! after 4 shots hit my very first good 4 iron. Im really very surprised that such a small correction with my swing can make such  am improvement.
        Simon said its the low irons that your technique has to be good, if not this is where it really shows.
Chris