Man, lots of good help and insight!
I was looking at some of the pieces I've made and there is a definite difference in leather although I have been using the same product from Tandy. I suppose it's like the butcher told me once, "Sometimes you just get a bad cow". Any insight for picking raw materials would be appreciated. Tandy has recently opened a store within about an hour and I can now go pick my double shoulders as opposed to getting what they pick.
So I gathered some scrap pieces and set out to look at if I could see a difference between pieces moistened (maybe 'cased' although I'm not sure) and/or oiled before dyeing. I just wetted the surface and held the pieces under water for 30 seconds or so and made sure all of the surfaces were wetted.
I then took pieces that were wetted, oiled one with Lexol (it was handy), and then dyed pieces that had only been wetted, wetted and Lexol'd, and dry pieces. At first glance the difference is significant. I am using two Fiebing's dyes, one that is a "professional" oil dye, the other is #201 Light Brown (the #201 is the one I generally use).
I will let them dry for a while and re-evaluate but first impressions are that pieces wetted dyed better and more uniformly. Pieces dyed after wetting and Lexol are better yet. Dry pieces that were dyed are less uniform.
One very interesting observation: When going through the scrap pile, I came across a piece I'm convinced was a better piece of leather and I'm pretty sure I can tell you which holsters I made from the piece. The flesh side is remarkable smoother and this carries out to the finished piece. The edges smoothed much better and overall, it just seems to be a better piece of leather. I purposed dyed a piece of this, dry, with the 'professional" oil dye. Ten minutes after I dyed the pieces, Iooked at them and questioned whether I had missed that piece. It was very slightly darker but in most respects looked like it was undyed. A quick sniff confirmed it did get dye but got lighter as it began to dry. Whenever I have used this, it's always been on wetted leather so I wouldn't have noticed this before.
When applying dyes, I use a wool dauber and add dye until it no longer soaks in.
When thinking about oils, I'm struck that a lot of the commercial preparations are different in one major aspect. Oils like neetsfoot oils are (I believe) oils without any water. Products like Lexol contain water and this seems to help absorption (although the water eventually evaporates leaving the oils). It seems this is important to the end product (I have heard that some people use oils or surfactants in the water used for casing and this probably has some effect). Keep in mind, I'm not casing in preparation for tooling but because most of the stuff I normally made has to be folded.
In respect to the dyes, it seems to me that the Fiebing's dyes I'm using are different and there are probably reasons to use one or the other. There wouldn't be two different products otherwise (this is my possibly erroneous thinking). The "professional" oil dye seems to have petrochemical type solvents (maybe toluene or xylene) whereas the #2 seems to have ethanol (this is judging by smell alone). Any insight anyone can offer would be appreciated.
Sorry for the 'stream of consciousness' and length of the post. It's just that I've not had folks with this level of knowledge and experience to ask before. In case you are wondering, I am a chemist and work in the chemical industry - so I'm semi-contaminated with maybe more technical knowledge than is necessary
Many thanks to all,
Mark.