It'll work fine. Just keep in mind that softer woods like Pine, Cedar and Poplar will absorb a lot of stain/dye and have a darker appearance than a harder wood like Oak, Maple or Mahogany.
I did a build with Red Oak neck and fretboard, but had a body of Cedar. I used Ebony stain on the Red Oak, but had to use some water mixed Acrylic Black Paint for the Cedar to get the same color as the neck/fretboard. Fretboard and bridge piece was stained Minwax Providential. Covered it all with Truoil as the final finish.
I have used fabric dye on wood in the past. Works fairly well. Also the vinegar and steel wool trick is great for achieving black. As always do a test piece first.
Milt - on woods like poplar and pine , i find you can get from a grey-ish barn board to a coffee colored result from the vinegar and steel wool process . but oak etc . will turn black easier . (depending on # of coats / soaking time etc) .
You are the master of this method and are absolutely correct. Guess I should have mentioned oak works best. I believe this is due to the tannic acid content. It also works pretty well on walnut and mahogany.
If anybody doesn't know the process. Pour some vinegar into a container. I use glass. Throw in a chunk of steel wool, let it sit for awhile (overnight?) then wipe or brush it on.
You're too kind Milt . lol. it is a really cool process to watch and try the first time . as it is more of a "chemical reaction" than a "stain " and you can actually see it getting darker before your eyes after applied .
i don't actually use it anymore , too many variables effect the outcome and you get inconsistent results . which is ok ,, but maybe not for a line of the same style guitars.
i use instant coffee for the most part now .
Haven't tried the coffee. Do you mix it thick or like regular for drinking?
i do 3 heaping spoonfulls in a half a cup of water . (or less) . nuke for 30 secs .. scoop out any creamy crap .. and apply . usually a recoat in about a half hour . even again sometimes ..
treating woods with a tea wash before the vinegar and steel wool is said to increase tannins and give better results on woods like pine and poplar.
I'd add another step - pour the mixture thru a coffee filter into a second jar to get rid of any little pieces of steel. With some of the oak pieces I did it raised the grain quite a bit giving a rougher feel, others only darkened and stayed pretty smooth. Also a test piece I never finished developed rust spots over time so be sure to put a finish over it (pieces with tru-oil never have shown rust spots).
I've had good results with liquid shoe polish that comes with the foam applicator, same method as yours John, many colours available