Answer: The manufacturer of Thompson Water Seal recommended that you use their product with a plastic sprayer with a brass wand, such as our Chapin Premier sprayer. There are no concerns about it eroding any of the seals inside of it.Click to see full answer. Similarly, you may ask, can you use a pump sprayer to stain a deck?A garden pump sprayer or a deck stain pump sprayer is the perfect tool to use to apply deck stain. You can finish a deck that would take days to stain by hand in a matter of a few hours with a pump sprayer.Also, how do you seal a deck with a sprayer? Start spraying at the corner of the deck farthest from the stairs or exit. Cover a section approximately 2 feet square, then roll over the area you just sprayed with a medium-nap paint roller to soak up any stain sealer that has puddled. Besides, can you thin out Thompson Water Seal? The old-timer came up with a similar formula in 3 parts linseed oil, 2 parts Thompson’s Water Seal cut with 1 part paint thinner. The paint thinner acts as a penetrating agent, making the mixture thin enough so that the active ingredients penetrate the wood.How many coats of Thompson Water Seal do I need? Deck Sealing and Staining Tips Thompson’s WaterSeal products typically need only one application, but you can apply a second coat of stain to darken the wood, if desired. However, you must wait for the first coat to dry (typically about 2 hours) and apply the second coat within 4 hours of applying the first coat.