I finally understood why i had irritation. Thin blades. Thin blades tend to flex when they cutting hair. This flexing action causes irritation. SE blades better. Mainly because they thick and and secondly because they hold firmly in place. Systems like Schick injector, GEM, Feather Artist Club superior to Double Edge. Because blade they have no flex. Cartridge razors caused me irritation because they had a thin blades held not firmly. DE razors caused me irritation because they had thin blade. Held relatively firm but still it's a thin blade. Today i've tried Schick injector system. What a pleasure to my skin. No harsh feeling finally. I tried Gem Micromatic OC before that. It also had this no harsh post shave feeling. But GEM caused me some irritation because how aggressive it is and how hard is to find right angle. Injector whole different story. Immediately found the angle, very efficient immediately, very easy to keep light touch because handle is plastic and it gives more weight towards brass head, very thin head helps to shave under the nose very easily. I have a proof why thin blades is bad. Look at this Schick 70's commertial and your life would never be the same. It's eye opener. They were right.