Re: Polish MY How To

Posted by Dave Houser on Apr 30, 2004

My previous BB ramblings:

This is revised from an old post of mine. Polishing is just a bit obsessive but hay so is boat building. Since, if you choose this nonsense, you will be starting quite a ways down the process extra care will be required to avoid sanding through the existing varnish at existing highs.

First, for the perfect finish that will reflect smooth lines you need to have the perfect faired epoxy surface. Plywood kayaks should have pretty fair lines but using a fairing board on the next to the last fill coat will have benefits in removing waves from the ROS. Some waves at the seams, from the stitching, seem unavoidable

Second, the epoxy needs to be free of those little dimple low spots that show up as shiny spots when you sand between epoxy fill coats. The answer is to remove all of the dimples before applying the last epoxy fill coat. Then wait two weeks for a full cure. Sand smooth to 220 grit. An even longer cure or elevated temperatures will minimize imprinting of the glass weave that seems to appear with time.

Apply four or five coats of marine varnish. I found that the foam brush strokes in the varnish are the same profile as the scratches from 220 grit sandpaper so to avoid cutting too deep I wet sanding with 320 grit on a �-inch-thick, rudder, closed-cell-foam sanding block (from the local boat shop) to assure I only sand off the highs. I'll use 220 grit on a wooden sanding block only to spot sand runs or sags. Be systematic to sand the whole surface and not over sand any areas. I then dry the surface with a towel and look for shiny spots. With a bucket of water I wet the sandpaper and spot sand only the shiny spots. I then rinse off the whole deck, dry and inspect for shiny spots and then repeat the spot sanding. When it looks good I wash, dry and apply one more coat of varnish.

Now if you get a good final coat of varnish and keep the dust, bugs and runs out of it you're done. If you can, wait two weeks for the varnish to harden and go paddling. After two weeks if you are still obsessing about having the perfect finish, it is time to polish.

Buy one sheet of every grade of wet/dry sandpaper from 320 to 2000 (building supply and auto paint supply stores you'll have to go to both). Wet sand with a bucket of water mixed with a small squirt of dishwashing detergent with 320 grit and the closed cell foam sanding block. Don't even sand the sharp corners (gunwales, coaming edges). Do the dry shiny test and carefully spot sand. Continue to systematically sand the entire surface minimizing over lap and avoiding the sharp corners with each increasing grit of sandpaper. Use a fresh bucket water with each grit. Be sure to wash the surface between grits with soapy water and a cloth and rinse with running water to remove the loose grit and dust. You can't really tell where you miss sanding at this point but don't worry about it you'll get it with the next grit but be systematic and try to not miss any spots. It doesn't take much sanding with each grit but don't skip any. There is no need to dry until the final sanding with the 2000 grit is done. Sometimes you may feel a piece of grit rolling under the sandpaper stop and rinse it off. When you complete sanding, wash the surface and towel dry. You are ready for polish.

Next you will need a power buffer or rotary sander. The perfect tool for polishing paint (varnish) appears to be the Porter Cable Random Orbital polisher with foam pads. All of the car detailers seem to be using them and the one sold by Meguair's is the one made by Porter Cable. I use a 7" diameter rotary sander because I had one and I used wool pads (they are cheaper than Meguair's foam pads). Also buy a bottle of each of Meguair's "Medium Cut Cleaner" No. 1, "Fine-Cut Cleaner" No. 2 and the "Swirl Remover" No. 9 (also at the auto paint supply store). Label the pads on the back with a permanent marker 1, 2 and 9. Polish the entire surface with No. 1 wash the boat and change the pad. Repeat with No. 2 and No. 9. Be sure to keep the pad flat on the surface and keep the sander/buffer moving.

You'll be amazed with the results. It took one day to sand and polish the deck. I don't think polishing the hull is worth the effort since I seem to scratch it up on the beach sand.

Follow the "clinics" on Meguair's web site: http://www.meguiars.com/

In Response to: Re: Buffing final coat by Steve Miller on Apr 30, 2004

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