No. They're "flashing" because they are
animated textures; nothing you can do in Hammer end can prevent it.
Dauby's tutorial doesn't include all the information you need because it does not address texture types, nor extracting the original texture--just in case you don't know--, so here's a mini guide for you:
Editing Original HL TexturesBy rowleybob (at least 55 edits later :P)
1. Read the tutorial Dauby mentioned from the previous post,
here.
2. Download/install Wally.
3. Copy the "flashing" texture from the orginal HL wadfile from .pak file or .gcf from these tutorials repsectively:
HL WON or
Steam4. Rename the animating texture to whatever you want using wally, just make sure you remove the
+0-9 part from the beginning of the filename, which is the only thing that makes it an animated texture.
For more info on Animated textures and all the HL texture types, check out
This little diddy by Slackiller.
5. Save the texture to a custom wad. The tutorial Dauby mentioned again should help you "wading" it up.
It seems involved, and it sort of is for accomplishing such a simple task. It will however double as a nice exercise for stuff you're sure to use again if you continue mapping