Travertine joints turning black


Active member
Sep 10, 2019
Houston, TX
We have had our pool almost a year now. All of our decking and coping are tumbled travertine pavers. All pock marks and joint lines are now black and don't look so good with the light color of the deck. I started to clean with a water hose and a nozzle, but when I did, the sand in the joints washes right out. Originally, the PB told me he used polymeric sand but this does not appear to be the case.

My plan is to clean all the sand out of the joints and pock marks gently with a pressure washer then refill and seal the deck. I wanted to get some expert opinions on the following:

1. Masonry sand or polymeric - Is one better than the other for preventing the mildew?

2. Seal or no seal - If I seal it, I want to use a high quality penetrating sealer that does not leave a surface sheen. I dont want the stone to get more slick. Any recommendations on a sealer brand? I talked to one here in Houston that has a pretty high opinion of his product, but Im not so sure (Texas Stone Sealers - The sealer I have used for other stuff are the Dupont (now Lacticrete) StoneTech products.



Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Sorry, I am no help with this one.. I just wanted to say that I thought that is what the Houston area Travertine always looked like after a year of two??

Let's see what our other members have to say..


Jim R.


Bronze Supporter
Jul 17, 2019
Prosper, TX (DFW)


TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
Just use a natural finish penetrating sealer. The glossy ones are just top coats. The newer poly sands aren't that sticky but hold together fairly well. If you cant pull the sand out with a toothpick its polysand. Be aware it doesn't stick well to itself. I never had good luck with just adding to the top of low areas. You really need to get the full joint opened and then reapply. It will stick well against the old on deeper vertical matches. The sealer works well to hold it all together


Silver Supporter
Aug 22, 2017
West Palm Beach/Florida
So I had the same problem as you and did this in November. It is generally not recommended but I did not care. Had the deck pressure cleaned and grouted and it still looks great. Still dont know how it will hold up in the long term but for now I am thrilled with the result. Still not a weed or moldy spot (ie black) spot anywhere and we had a very wet winter.