The VHT and SEM vinyl and plastic dyes are far superior to the Dupli-Color, which isn't bad stuff itself really. Gloss Dupli-Color is definitely too much; I've seen it used where someone thought they'd get the "permanently Armor-Alled" look, but it just came off looking cheap, almost plasticky. This not a problem with the SEM "gloss" dyes, however. They are thinner in consistency and allow more of the material's grain to show, in fact they hardly affect it. Hands down, the SEM stuff is the best dye out there. Yes, it's expensive, but not as expensive as doing it twice. If you're doing carpets, use either the SEM or the VHT, period. Done correctly, they won't stiffen the fibers into a bristle brush. The VHT is less expensive, too. Krylon Fusion is the best I've used for hard plastics, as even the interior dyes don't seem to sink into the plastic enough and seems kind of fragile (more on that below). However, the color selection is (was?) a little weak when it comes to car interiors; obviously black isn't an issue in gloss, satin, or flat. This is also true of the VHT and Dupli-Color lines--Plasti-Kote, too, now that I think of it. I have no experience with the Plasti-Kote dyes, but I'm not real fond of any of their other products so that's probably why.
One note on the SEM stuff: Though it's now discontinued, their 15463 Gloss Cabernet is about as close to a dead match as you'll ever see for a late '70s-'80s Mopar red interior in both color and sheen. If you have one of those interiors and need to match a part, it's well worth calling around to find old stock on a parts-store shelf somewhere. To my knowledge, when it was discontinued they did not issue a factory return; it was merely a "sell until depleted" situation, so I'm sure there's still some out there. I bought several cans of it for my LeBaron; it was virtually perfect on the dash pad & rear seat. I still have two cans I'm keeping "just in case" even though I don't have any red interiors anymore.
A few tips:
1) Don't rush it. If you need to be somewhere in two hours, don't even start. Get a time cleared when you can do everything you need to do at once, step by step. Take your time--it will show if you don't.
2) Follow the directions on all products you're going to use to the letter. They make it, and they know how it works. Yes, keep shaking it occasionally (people forget this all the time).
3) Make absolutely sure there is no protectant or Armor All whatsoever on them or you're wasting your time even trying. Try a commercial wax & grease remover (I use U-Tech R859 or AutoBody Master 5900 because I have it, but any paint jobber will have their brand of the same stuff). Test on an inconspicuous area of the vinyl, leather or plastic first to make sure there will be no ill effects on the "good side". I have not had a problem to date with the R859 or the 5900).
4) Make sure the panels, seats, etc. are white-glove clean before you attempt to dye them. Then clean them again. It's that important to get good results. Warm soapy water, time and again until they're perfect. Make sure you leave no soap residue.
5) Use a preparation product, such as SEM 38354 (plastic & leather) or SEM 38343 (vinyl) immediately prior to the dyeing process. This stuff will really make it stick; I've used both with fantastic results, but I truthfully have not tried the 38354 on plastic yet. I probably will in the near future, since I'm going to be doing a color conversion on my Imperial.
6) Typical spray-paint rules are in effect: yes, the stuff will run, sag, etc. Reflections are your friend; just lay enough dye on that you can see reflections from a steep angle (think about the view of your hood while driving) and make sure your coverage is even. If this is at odds with the dye manufacturer's directions, listen to them--not me. :icon_biggrin:
I don't sell any of this stuff, nor do I work for any of those companies. I'm just passing along what I've found works for me. I used to get SEM, VHT, and Dupli-color, as well as Akzo-Nobel (Sikkens, Lesonal, U-Tech) and AutoBody Master products all at cost so that's what I've used. Others may have had better results with different products and if that's the case, please share. I'm always looking for better stuff!