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How can I remove runs in varnish?

waynew's picture

Hi Peter,

I am applying a good quality marine varnish (z-spar) to an exterior door casing and associated trim and had a few runs early in the piece after the second coat which was applied at full strength. Sanding between coats using 320 grit along with thinning the varnish by 10-15% seems to have helped a little but I noticed that the sanding is thinning the surrounding areas along with the runs. I'm up to my 4th coat and will probably apply a total of 5-6 coats over the mahogany. Can you suggest a method to remove the runs without removing the surrounding varnish and stain?

Many Thanks,

peter28's picture

(post #125730, reply #1 of 2)


I know what you're going through. Here's a few ways I fix those.

One of the best ways, I feel, is to lightly scrape it with a razor blade. First be sure it's reasonably set up. Try pressing your thumbnail into the drip. If it's very soft, LEAVE IT ALONE. Once it hardens a bit, use a new razor the same way you would use a cabinet scraper. Lightly scrape the drip and run until it starts to flatten out.

When using sandpaper try and keep it as local as possible.  The idea is to just cut down the " hill" until it flattens out. I know this is easier said than done sometimes. I know you probably went with the grain right? Believe it or not, I'll start with the grain and then lightly perpendicular for a few strokes and then back with the grain. When going against the grain, I might just have a small piece of sandpaper on the tip of my index finger or the side of my thumb..

I'll even follow that up with a light rub with a gray scotch pad.

You can then wet this area with a bit of water or mineral spirits and see if all is well. If the color is a bit light, dry it, take a little of your stain on a Q tip or a small brush and keep them fairly dry. Tap a little color into the area, count to eight, make a fist , and lightly tap the area with the soft part under your baby finger. (like you were pounding your fist)  Do this lightly and the color will be dispersed with no application lines showing.

it sounds like you didn't get them off soon enough(in the first couple of coats)After you have some more body built up you may consider wet sanding with six or eight hundred paper and then give it one final coat. If you use water for wet sanding, a drop of dish detergent will act as a lubricant. Just be careful, water acts as a very aggressive lubricant. You can cut through the surface very quickly

This was a good learning experience.You'll do better next time.

Peter Gedrys









waynew's picture

(post #125730, reply #2 of 2)


That all makes sense, thank you for summarizing those points so clearly.
Your right, I should have taken more time and correctly addressed the problem eariler, the localized sanding seems to have taken the remainder of the runs down to a point that now looks very acceptable. With a few more coats and a little wet sanding it will look quite good.

Thank you,