Whose batim do you use for your basic gasos and why?
For non Edah, avodas yad retzuos I use from 2 of the well known and oldest makers under respected hechsherim. One wholesale customer recently told me that he got feedback from some of his customers that the retzuos I provided (I don't know when) were taking on a reddish brown hue.While well aware of this issue, I haven't seen it myself on the retzuos I have in stock nor heard about it from any other customer. For some reason, on a rare occasion, the paint can take on this hue. I assume there's some chemical reason for it and I've even see it return to black. (Rav Elyashiv held it was still kosher with this hue.) As this client isn't aware of this metzius, he immediately assumed that "my" retzuos were not good quality. I explained to him that it has nothing to do with the quality and happens on occasion to any retzuos, including those with the best name, hechsher and highest price. Have you experienced this is the recent past?
There is a top maker who does a run with paint made with black aniline pigment rather than the paint that the Badatz and others permit. While it's known to be 100% synthetic and there's no concern that any of the pigment is from animal bone, it is known to often have this problem.