How are you applying the pressure and for how long?
A strong man (one of my patients), over 200 pounds compressed the plates together by pushing down on a table. We started off with light pressure, then increased pressure to the point of extreme. We did the same with temperatures ranging from upper 200's to the low 300's F. The timing was varied, from 5 seconds up to about 60 seconds. Most were in the 30 second area. Following what others have done. Have read many posts and watched many YouTube videos.
I am not saying it didn't work, in fact, it did work pretty well with my worse oil making strain, Strawberry Cough (I have to admit, the rosin was some of the most potent oil I have had). It did produce some with Querkle, but with 4 more strains, it did not even squeeze a drop, just saw a lot of vapor escaping but nothing on the paper.
It seems this method is very strain selective, much like that of solvent extractions.
Here is a first extraction of my best oil making strain.
This is the remainder of the second extraction of my best oil making strain. I used about 1.5 ounces which produced about 7 or 8 grams of concentrate total, considering first and second runs.
My initial plan was to compare the QWISO method to the Rosin press method with my 4-G strain. I set aside buds just for this comparison. Well, when the "press" did nothing with that strain except put off a very nice aromatic vapor into the air, I decided to try my other strains.
TGA 9 Pound Hammer, which produced no rosin, reacted similar to the 4-G with the iron.
Original Bubblegum, surprised me, also produced no rosin, and this is one of the most gooey strains I have ever grown. It is not sticky, just gooey.
I also tried Chemdog #4, not happy with this strain period.
Again, I do admit that the Strawberry Cough rosin impressed me. I could say it was some of the best oil I have vaped and smoked from this strain using the rosin method. I am certain it would be even better with a true press of quality.
Over all, it seems the rosin press method is very strain selective. I sure did waste quite a few buds through all of the trials I put them through.
Am I missing something? Is it technique? Tools, strains? Hard to say since my SBC did produce product.