The orangish gunk is "mildew" in the early stage. it will start out with pinkish/orangish look and later turn black.

I do not have travertine and therefore cannot tell you what to use for cleaning.

I usually use bleach water to kill mildew on grout, not sure if it is safe on travertine or not.

After you get it clean and free of mildew, be sure and rinse well, dry with an old towel, and use a fan to blow air into the shower leaving the door open for a few hours after using the shower, every time. This will help prevent mildew/mold.

If soap or bath wash is left on the tile/grout it will get yucky faster.

"Soap" leaves a residue on tile and grout, we call it "scum". Best to switch to a body wash, rinse well, and squeege after each use of shower.

Thanks Krissie. I did not know the orange look was the beginning stages of mildew. I have caulking around my tub deck with it and I've tried everything including bleach to get it back white. I'm guessing the builders used the wrong caulk, then?

If mildew gets in, under, or behind caulk it is necessary to remove the caulk and put new in. Bleach will not penetrate into the caulk. Mildew/mold will penetrate into the caulk.

Builders may have used the right caulk, but, did not apply it correctly for a good seal.

I'm bumping this message since I am having a similar issue with my Travertine & grout. I thought I'd seen messages in the past outlining best practices, but am not searching correctly or in too big a rush.

My primary problem is I probably have not sealed often enough -- will change my habits once I can correct this problem!! -- then DH decided NOT to suck the cool, air- conditioned air out this summer so he began turning off the vent as he walked out of bath. We have a very nice in-line vent installed in the attic space above our vaulted ceiling Master Bath with a timer on the vent!! (Not sure where he got the idea he was saving electricity?! We live in GA so its pretty humid & he grew up in Louisiana . . .)

So now I'm attempting to get back before sealing again. I have a issues with a few "pores" that have mildew where a razor sat, so also want to clean that out. There is mildew on some grout which seems more stubborn (or is stained).

My primary cleaner that works well is TileLab "Everyday Cleaner". It does a great job with the orange gunk & soap scum (even for water spots on the glass door & walls). I use a soft vegetable brush on difficult places & soft toothbrush on "sanded" grout. I have read that Hydrogen Peroxide or Tea Tree Oil will kill spores & clorine bleach will bleach the color. I know I shouldn't use clorine on my Travertine, but am interested if I used the Clorox Bleach pen on the grout & washed soon & completely if I'd be safe or if Peroxide or tea tree oil will hurt the travertine. Some threads suggest an Oxy-Clean solution, as well there are Non-clorine bleach pens that might be helpful. I want to be expedient & correct my problem before it gets worse.

Thanks for any advice you can give me.