catzooks.com

Wetsanding and Varnishing links

I've had these links in my files for ages. Time to put them in.

• (link) talks about wetsanding & steel wool
• (link) varnishing a kayak. One of the interesting points One Ocean Kayaks makes is that one part varnish cures by allowing the volatile solvents to evaporate. Two-part varnishes cure by "reacting together to form a solid which is superior to varnish (or other single component systems) in all desirable mechanical properties. This includes hardness, scratch resistance, solvent resistance and surface quality, namely gloss."
• (link) varnishing (& steel wool, wetsanding)
• (link) Sanding to a mirror finish

And of course, I mentioned it a bit here. I'm using real running water now - and it works a LOT better than using a bucket. Using the bucket you sand small particles into even smaller ones. Using running water, the sanded off particles are washed away.

Wetsanding

So with Yet Another Black Layer on, more sanding beckoned. And I finally figured it was time to take the tape off. First the blue stuff, which was pretty easy - very little extra dripping. Most of the problem was because this tape folded into ridges, those ridges were sanded away, and I couldn't pull off the entire thing in one piece. I probably used more than I needed to in the bow, there wasn't enough dripping to justify covering the entire thing (although it does provide protection against drips from the brush, and that can be equally important).

Next, the green tape. This is great tape, it came right off. Just be careful to pull up toward the black line (so the tape is being pulled up toward the black). I also lifted it off with a very acute angle, so it wouldn't cause chips in the black. Occasionally I scored the black with a knife, or used my knife to get the tape started again - but overall, it looks great.

There are a couple spots where the different pieces of tape overlapped, and there's an edge (which can be cleaned up fairly easily). There are other spots where the epoxy squeaked under the tape and so the edge isn't quite as sharp as it should be - and this it's much, much harder to get rid of. Make SURE the tape is pressed down hard (I thought I had)!

Next: Wetsanding. Wetsanding is highly effective. Sanding this way is just awesome. The paper sands quickly, it never clogs, you don't have to wear the respirator... You just get a bit wet, and it's a bit messy. Glad we had a warm week.

The objective is to get everything to have the "dull" look - it's starting to appear here. To control the water output, I went down to Orange Borg, bought the cheapest hose I could find and a couple small drill bits, and then drilled holes into the first six feet of the hose. This turned out to be too long - two feet was about right.

While the hull is wet, it's really hard to tell what needs sanding, especially on the wood. I finally took the plunge and decided to draw on the hull - and cover it in permanent marker ink, then sand it all off (the idea comes from here). This method turned out to be very effective. It's really easy to see what's done and what needs a bit more sanding. I only wish I'd done it to begin with (so I would have removed less epoxy).

Perfection.

I then marked up a few spots which needed more, and then sanded down port side.

(28 images)

More black, black

Well, last week I managed to sand through a couple spots, and left a few zebra stripes, and so after a wee bit more sanding it was time for another layer of black. I sanded down with 100-grit on the gunwale edge, and used the random orbital on the entire thing - probably a mistake, as I took off the black on the backing plates. I've come to the conclusion that 1) for the black, it's worth using 100-grit paper so you don't go too quickly (and it doesn't leave the same scratches), and 2) you're always after the least number of strokes with the paper. One stroke too many, and it's another layer of black that has to go on.

There were a couple spots that needed another layer of black - I sanded through the black below the chine, on the backing blocks, and had the zebra look where the gunwale tape "stepped down" to the hull itself.

I did the next application on a Sunday so I didn't have to do it overnight. The plan was to only lightly apply black to the areas that needed it, but I covered most of the black along the gunwale (although I didn't paint into the gulley between the gunwale and hull - already enough epoxy in there). The first application was two 3-squirt cups. The second application was only one, and I used up not quite all of it. It's getting cooler here, so the epoxy didn't cure quite as quickly as it did last week - but it was still far enough along for the next step. And the third application was one 3-squirt cup that I finished off, lightly applied.

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Black on the gunwales

Finally got the black on the gunwale. This took a bit of doing - had to wait for the time to do it, and to ensure that the next day I could stand not having slept.

The way I've been doing these multiple applications of epoxy 3 hours apart is by doing them overnight. With two small kids running around, this is pretty much the only way to go (other than forcing the kids on Tamara, which isn't fair).

You might expect that I'd be a wreck after these sessions, but overall they haven't been bad. I try and wait for a weekend, but given this experience I may try during the week.

The trick is this. Get the kids to bed early, and dive in with the first application (I also did the transom and the blue-marked spots on the deck). This takes the longest, usually an hour; done at 8pm. Come back 3 1/2 hours later (11:30pm) and do the second layer (30 minutes). Set the kitchen timer for 3 1/2 hours and immediately go to sleep on the couch. Come back 3 1/2 hours later (3:30 am) and do the third layer. Go to sleep in bed. If you need a fourth application, do it when you wake up in the morning.

Working like this, I got the black done on the gunwales, and was pretty functional the next day. The hardest part is getting to sleep at 4am - I was pretty awake.

For these applications, I used the recipe of 3 squirts epoxy/207 hardener, 1/2 tblsp graphite, 1 tsp (packed) 410. I'm not sure this made a huge difference, but it does seem to be a slightly lighter shade.

Finally, after a mere nine hours after the last coat, I returned and sanded down what I had applied. It was shockingly easy. The epoxy hadn't cured rock hard yet, and as a result it balled up and fell away. I could sand down everything, and didn't really need the dust mask. I'm not sure if this is due to the 410 or because of the only nine hours, but sanding sure was easy this time.

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Taping the gunwales

Time to get the first layer of black down on the gunwales. I started by sanding off the tape - this was easy, although I wound up sanding off quite a bit of the bottom edge of the gunwale as well, and I'll have to go back over with another layer of black (sigh). Once that was all clean, I taped both the upper and lower edges. The upper edge needs a sharper line - something I have meant to do since I put the black on the hull. I put a few nice curves in, then covered up the remainder with blue tape.

I removed the tape on the "top" edge of the gunwale - although I should have put some back so I wouldn't get drips on the edges. I then trimmed the bow down a bit, and I think I'm ready to go.

(15 images)