When you first go to a new customer that has an existing stain or sealer on the wood most wood guys, including myself will strip off whatever is on there and start from scratch. One reason is that we are all trying to build a business and it is easier to re-coat when going over your own work. We do it the first time for a higher price and then offer a discounted future maintenance plan. One of the hardest parts of the job now is identifying the existing coating and having both the a good stripper and the right stripper for the job. Some of the harder ones are Behr and Sikkens which some contractors even walk away from. These usually involve extra dwell time, possibly a second stripping, and usually more sanding than others jobs. Knowing these things will keep you from estimating correctly and not losing your shirt on a job. With so many water based products there are times when a solvent based stripper may be a better choice than a sodium hydroxide based stripper. One way is to ask the customer if they know or if they have the old can. Unfortunately, a lot of this comes with a bit of experience. We all love getting a new deck or one that is very weathered because it is easier. I give you credit because I see a lot of other trades that say "yes" to the customer and bleach the deck and slap on a coat of solid stain, get paid and walk away. This deck usually starts peeling the next year and one of us get the call and then it is a real mess and expensive to fix. Feel free to ask as many questions as you have, this can be a nice add on if it is done right.
