These diamond the akron lamp & manufacturing co. 6 are in very good to excellent condition for their age. The post patent iron would be very good. The one with no logo was sent out to distributors prior to it going on sale to the general public.It was sent out sometime in 1935 prior to its patent. On the lower part of the handle (note: photo) it reads pat. This is why there are no other markings on it. 4 is what most people see up for sale. 6 model that was made after the no.
Each iron weighs 5 lb. Wide (at the widest part of the iron), and 6 1/4 in. Condition: make no mistake, these irons have been used as you can clearly see from the photos. Some of the finish on the wood handles has worn off.
Also, you can also clearly see that there are slight burns on the finish on the right side of the iron. It's just a guess, i would say that they both have under a few hours of use, total.
I did not try it out. I have several dozen different antique irons and have done extensive research and have never came across a pre & post-patent models like these. I have also sought out a few iron collectors and have discovered that the maximum amount that were produced prior to the sales to the general public was under 100 units.I would surmise that the pre-patent one may be one of a dozen left in the entire world.