That is correct, as Danne Honour said, once you get a good one you are set. Since backcrossing to good quality will net you more good quality feather lavender.
Edit.
I've seen really Bad ones, but can't seem to find them now, really old ones from like 20 years ago
Not at all.
lav^g/lav^g = Good quality Lavender
lav^b/lav^g = Bad quality Lavender
lav^b/lav^b = Worse quality Lavender
So if all You have is Bad quality Lavender it does not mean that you can't breed enough to get good quality Lavender
Let's put it this way: two good quality feather lavender when mated together can only produce good quality feather lavender, but females seems to be tricky to identify as good vs bad
Let's just treat this traits: Good feather vs bad quality feather as allelic mutations, there are plenty of allelic mutations on Chickens to think that it's imposible that Lavender can't have one. Seems to be of a recessive nature. lav^b(bad quality)/lav^g(good quality)
I desagree in the believe that Fray has anything to do with the bad feather quality on Lavender, but I agree that only breeding from good quality feather lavender birds is the best way to go about it
Fry is not on the same chromosome as Lavender therefore not linked. To my understanding Lavender Coturnix Japónica Quail do not have the bad feathering as some lines of Lavender Chickens and both mutations are allelic and found on the same chromosome
Danne Honour, one of the best and meticoulus breeder I've seen in my years of research. No research have been done in the Shredder/Wingpatch fenotype on many Lavender colored breeds, some people believe it's a mutation that is vey very close linked to Lavender and that to break the linkage one...
Furness is basically a Melanized form of Wheaten like Brassy Back but instead of e+(wildtype) it's based on Wheaten. Search for Furness Cochin and you will see what is the Furness look
You would be surprised of what you get if you start test breeding buff leghorn.. Here is the work of Dane Honour and Brian Reeder.
http://web.archive.org/web/20060504124933/http://www.panopliageneticus.com/testmatingwheaten.html
Dark Browns are one of the very few breeds that are based on eb, red enhancers and the rest is pretty wildtype in nature, so if you are looking what a hen with eb alone looks like, then look no further than the dark brown leghorn hen, other breeds that have eb like partridge wyandottes or...
In this case I must admit that Google is Wrong, those are 55 flowery, in Ancobars the females are extended black, mottled and barred, the female on the pic is clearly wild type(salmon breasted) mottled and barred.