Before sealing your travertine, it must be thoroughly cleaned. Wax or polyurethane coatings must be stripped off.
After removing these coatings, if any, the tiles should be cleaned with a neutral cleaner -- one that is free of bleach and alkalies. If your travertine is badly soiled, or if you are refurbishing old travertine, an alkaline stone-cleaner can be used to deep-clean grease or dirt buildup When your travertine is completely clean, dry it thoroughly with an absorbent cloth.
Let the area dry for 24 to 72 hours.
Choosing and Using a Sealer
According to Marblelifecom, there are two basic choices to make when considering a sealer: Do you want a solvent-borne or water-borne sealer and do you want a topical or penetrating sealer? Solvent-borne sealers are easier to apply than water-borne, using a wipe-on/wipe-off method. Water-borne sealers may be more durable, but you must take extra care in removing excess sealer or it may create a dull haze on the top of the travertine that requires the skills of a professional craftsperson to remove A topical sealer sits on top of the travertine and adds a visible shine or change to the stones' appearance.
A topical sealer may help make mismatched or permanently stained tiles look more uniform. If you like the natural look of your unsealed stone, use a penetrating sealer.
A penetrating sealer adds the protection of a sealer without changing the surface look of the stone Consult your dealer when purchasing the travertine to learn which sealer is best for your stone and application Apply the sealer according to the manufacturer's instructions. This typically entails using a lamb's wool applicater and mopping the sealer on in thin, even coats and then allowing time for drying before the travertine is walked on or used.