There are at least two ways to approach this.
To start, select the character and go to the Surfaces panel. Hands are part of the arms, so you want to look for the Arms surface - expand the character, then "Surfaces" and click on "Arms." In the settings for that, you'll find "Base Color". If you hover over the little box on the left, it will give you a path to the texture that makes up the character's arms and hands.
For this character, given where I've got my Daz content stored, the path is D:\DAZ3D\Content\DIM\Runtime\Textures\DAZ\Characters\Genesis3\Victoria7\V7ArmsMapD_1004.jpg. Your path will obviously vary depending on the character and where you have your content installed.
What you can then do is make a copy of this file, store it elsewhere. If you look at it, you can see that it's the arms and hands "unwrapped," with the fingernails then shown separately.
Now, you have two basic approaches:
1) You can simply modify your own copy of the texture. Then, to apply it to the character, click on that little Base Color square you hovered over, select "Browse," and select your modified texture instead of the original texture. There are a couple of caveats to this:
- The best way to do this is to use Gimp or Photoshop, create a new layer on top of the base texture, and paint on the new layer. That way you can erase stuff you've added without altering the base. However, you have to export the file as a JPG - Daz won't "understand" a Photoshop or Gimp file directly. Note that there's nothing magic about the exact file name (e.g. V7ArmsMapD_1004.jpg) - that's just what the artist chose. You can name the file anything you want.
- It may take a couple of iterations to get the redness where you want it and looking the way you want. If you modify your JPG multiple times, Daz doesn't seem capable of picking up the changes unless you restart it. It caches the original version of the file or something like that. So you may have to go through a sequence of exporting "file1.jpg", "file2.jpg", etc. and re-selecting a new file name each time in order to see your changes.
2) The other approach is similar. Here, however, you just create the overlay, not the entire texture, with transparent bits where you want the base texture to show thru. Then, you install this
over the base texture using the Layered Image Editor, which is one of the options when you click on that little "Base Image" box. Some of the "makeup" products on the Daz store work this way.
Personally, I think #1 is a bit easier, but either way will work. The second approach supposedly has the potential advantage that you can save it as a "Layered Image Preset," which makes it a bit easier to apply again later. But I haven't figured out the full mechanics of that - I think the file you create has to be somewhere within Daz's content hierarchy for that to work nicely.
Getting things looking right takes a bit of artistic skill - I'm not going to mislead you. Certainly just "reddening" the fingers shouldn't be too hard - you can just paint over the existing fingertips with a translucent reddish color. Doing actual blisters would be a bit more challenging.
Hope that helps...
