This product from BAL is useful if grouting with BAL grouts.....
BAL Protective Sealer
A water-based polymer emulsion specifically formulated to provide a temporary, protective coating to ceramic tile/mosaic surfaces during the grouting process. Suitable for use with all BAL grouting products.
BAL PROTECTIVE SEALER is a water dispersible temporary sealer designed to protect the tile surface against discolouration which may arise when using pigmented grouts. It is not a permanent sealer.