Insl-X Max Block is the next generation of water-based primers, formulated to provide advanced stain-blocking properties when compared with other typical water-based primers. Max Block can be used for many common household stains including water stains, as well as smoke and nicotine stains, and wood knots. It is also ideal for tannin bleeding type woods such as redwood and cedar-providing a lower-VOC option in lieu of an alkyd-based stain-blocking primer.