How pure can any strain be?

This has been rattling around my brain especially after reading the posts to that "Don't kill males thread" . Males spread their pollen far and wide as much as naturally possible. Therefore, seedbanks that grow 20-30 strains cannot physically guarantee any of their strains are "pure", or even really F1s. Unless they have 20-30 totally isolated grow rooms for each strain, the females will get pollinated by any flowering male in the area. At $5+ a seed (cheap ones) that little fact must be kept on the super down low by breeders. I just think any grower should be wary of any "pure strain" claims.

Alot of times the grow rooms are isolated. The ones that are done on a large scale usually will be professional breeders, and know what they are working with. They will use a technique called SCA. This is where they will take a number of potential females and mix them all with the pollen of one male. This way they have a control for one side of there breeding project. The other thing they will do, which is a way to cut a HUGE amount of time off your project, is to do GCA. This is where they will mix the pollen of many different males and then pollinate a number of females that are chosen to be compatible. They will grow out the F1s, looking for that magical cross. Then they will select a hand full and start crossing, cubing, back crossing, ect. Until they have a stable strain that is incredible. This technique is interesting to me, because you could never replicate what you have done, but you know that know one else can either. Also it takes years off of the time you would normally take to do these crosses one at a time. :) Both of my favorite breeders use this technique, DJ Short, and Soma. Thats how soma comes up with alot of his crazy strains, that are so good, so fast. And I can personally assure you that all of his seeds are 100% pure. They grow out 15% to 20% of the stock before selling it just to make sure its uniform, pure, and over all what they are looking for.

The way I do it is keep all my males together and isolated, and keep all my females together far away.
When it is time to pollenate, I take a paint brush and a small envelope, and carefully harvest pollen from the chosen male. I then seal the paint brush inside the envelope and tke my selected female away from the other ladies and pollenate just a couple very low buds with the paintbrush. That branch gets a label giving the cross. You can do several crosses on the same plant this way. The female is allowed to rest a couple hours before being misted with plain water and then returned to the flower room.

Very cool. I did not know that. Thanks guys.