So yes, gibberllic as will the colloidal silver. Also, you have a 50/50 shot of getting a female to grow male flowers with a solution of ground up aspirin (2 tablets per gallon) sprayed on the leaves. (Cheapest way to go)
The BEST way (meaning the lowest chance of getting hermies), which was popularized by SOMA btw, is to grow the female plants past their maturity without harvesting. This will produce "banana shaped" male flowers which are capable of pollenating other females. Save the pollen from these flowers and use it on your next go-round on some fresh females and you should have femenized seeds.
One thing to remember is not to self-pollenate your plants. This, or so I have heard, often produces hermaphrodite plants from the seeds. Like I said, use the pollen from masculinized female plants to pollinate future females if you want FEM seeds. Its a long process, but worth it if thats what you want.
I personally grow lowryder, and I just kill off the males before they are a problem, less hassle. Femenized seeds are highly overrated if you are the one who has to make them.