Today’s finishing question: How do you prevent streaks in wipe-on poly finishes such as Arm-R-Seal or Minwax?
This is a pretty common issue with wipe-on poly finishes, and it has a lot to do with how thick you apply the finish. But before we get to applying the finish, let’s talk about applicator prep. You want to use a clean, lint-free cotton rag, like an old T-shirt. Woodcraft Supply sells a good box of lint-free rags if you don’t have any on hand.
Next, fold it so all the cut ends end up in the center. Fold one cut end to the halfway mark, then fold the other side to the halfway mark, so both cut ends meet in the middle. Then fold it the same way in the other direction. This gives you rounded folds on the edges, which cuts down on streaks caused by a raw, cut edge of fabric dragging through the finish.
Once your rag is folded, you need to prep it so it doesn’t just soak up all the finish instead of putting it on your project. A dry rag will pull finish straight into its center, leaving less available for wiping onto the wood. To prevent that, dip the rag in mineral spirits to pre-charge it. Squeeze out the excess first; you’re not trying to dilute the finish, just taking up space in the rag so it can’t absorb as much.
Once the rag is prepped, apply the finish liberally. You want enough thickness on the surface for it to slump and flatten out, basically self-leveling. It takes some practice to get a feel for how much pressure and how much finish you need on the rag to get a streak-free result. Too thin, and the finish won’t have enough body to self-level. Too thick, and you’ll end up with a goopy look or ripples as it dries. Now, when you apply it, you don’t want to just slam the rag straight down, as that is going to leave a mark; you want to glide in and glide out, like you are playing with an airplane, practicing your landings and takeoffs. Then always work off your wet edge.
Final note: sand adequately between coats. If you see streaks in the second coat, they’ll most likely telegraph through into the third, and of course, a good surface prep will help you get a quality finish.
I’m the owner of Benham Design Concepts, a mixed media art studio where I design and build custom furniture and other works of art using wood, glass, stone, and various metals.
In this blog, I talk about the art I create, my journey, and the things I learn along the way.