Tinting frustration

Is it really so hard to tint lenses? We’ve been trying to get new outdoor glasses made for my daughter since January. Time and again they come back from the lab too light, and most recently the wrong color. Is it really more complicated than leaving the lens in a bath of the correct dye until their measurement device shows it to be the tint strength we requested? This same lab has done it before so I don’t know why they can’t seem to do it again. It has been so frustrating that I have looked into starting my own optical tinting lab in the basement. It looks like it would cost $1,000 to get started, so not really practical. But much like other impractical things, like getting a second shower in our house, or a new kitchen, its nice to day dream about. What I’d get would be a BPI Digital Mini Tank 4 ($566.45) to dye the lenses (when you buy one they include a starter kits of all the chemicals you need), the dye we use for my daughter’s lenses (BPI FL-41, $30.70), and a BPI Mini Meter photometer ($299.95) to measure the lens transmittance (what % light they let through). 

BPI Digital Mini Tank 4 ($566.45)

($30.70)

BPI Mini Meter ($299.95)