When to Touch Up Varnish
The look of your brightwork says a lot about the pride of ownership that a boater has for his/her boat. A rule of thumb that you can use to tell if you need a touch up or a major overhaul of your brightwork is as follows:
Use a mild, soapy solution to wash thoroughly and get rid of all the grit and grime that has collected. (Hopefully, you do this more than once a season.) Rinse thoroughly with fresh water and dry. Take a towel and wet it thoroughly (make sure it is dripping). Drag the towel across the varnished surface. If the water that the towel leaves behind beads up the varnish is still in good condition. However, if the water that is left sheets or lies in flat streaks, you should plan on a light sanding and applying a couple of coats.
When A Varnish Touch Up Is Too Little Too Late
The only thing worse than going to the dentist is scraping varnish down to bare wood, sanding smooth and starting the arduous task of rebuilding 8 to 10 coats that will give you that “mirror” finish.
You can only patch the small abrasions and scratches so long until, ultimately, moisture has crept under the varnish and into the wood. This saturation of fresh and salt water will show up as dark patches under the still shiny finish. You will also notice lighter patches as the hot sun has glared down and has started to separate the varnish from the wood because of the moisture or perhaps the impact of dropping something on the varnish. It is at this point that you have no choice but to restore the integrity of the surface of your brightwork by scraping it down and starting anew.
Use the following as a step-by-step process to get brilliant brightwork consistently.
- I like to use a heatgun and scraper to remove the old varnish. This seems to go faster than sanding alone. In tight spaces you may have to just use sandpaper and lots of elbow grease. You should practice on a spare or out of sight piece to make sure you can control the scraper. Be careful not to make gouges in the wood.
- Once the varnish has been removed, sand the wood smooth using finer and finer grits of sandpaper. You may want to start with 80 grit to get all the rough areas and work up to 400 for that “babies bottom” smoothness.
- Before starting to apply varnish, make sure all sanding dust has been removed. Use a tack cloth dampened with a thinner that is recommended for the varnish you have selected. I lean toward varnishes with a high U/V rating. They tend to hold up longer in the sun.
- Stop! Don’t shake that varnish can, this is not paint. Shaking or even stirring will introduce bubbles which will show up on your brightwork. Most likely you don’t need to mix the varnish but if you feel obligated to make it move around the can while you watch, just swirl it slowly.
- Always filter the varnish by pouring from the can through a fine filter, or nylon stocking, into a small, clean container before applying each coat.
- For the first coat, thin the varnish with the compatible thinner 50/50. This will act as a sealer coat. Subsequent coats may be thinned if necessary to provide a good flowing viscosity.
- You may use a “real brush” or the disposable throw away foam brushes. Just make sure each is thoroughly clean and, if using a real brush, pull to remove any loose bristles or they will end up in your varnish work.
- Let the varnish flow on and only try to cover a small area at a time. Look for brush bristles, bubbles and holidays (spots that you missed) as you proceed.
- Make sure that each coat is completely dry before attempting to add another. Lightly sand with 400 grit paper between each coat.
- Repeat until you have 8 to 10 coats and that “mirror” finish that will be the envy of all at the marina.