Finishes for hybrid projects

[Brad Campana]

I've recently started casting my own resin projects. I wanted to know what you all use to finish hybrid bowls, pepper mills. When I turn hybrid pens I use multiple coats of CA and use magic juice to finish them. It really makes the resin stand out and the finish look great. However, I don't want to use CA large projects and I would like to stay away from lacquer. I'm finding that I see micro scratches after sanding (even after using sanding sealer, Yorkshire grit and microfine grit). When I apply tung oil I notice that the resin doesn't shine or stand out. Would like to know your process.

 

[John K Jordan]

I'm finding that I see micro scratches after sanding (even after using …

I can’t advise on finishes for anything but straight wood.

I do use a way to find scratches before they are sealed under a finish. I use two things, a small, bright light source on a flexible neck, and Naphtha. I position the fixture so the light is at a glancing angle to a part of the work. I put some naphtha on a small piece of paper towel and apply it to the wood. At first, the liquid soaks in a gives a wonderful preview of what the wood will look like with finish. Then, just as the naphtha starts to evaporate (and it evaporates quickly) I examine the wood under the glancing light. This tends to make any remaining scratches visible since naphtha in the scratch doesn’t dry as fast as on the surface, making the scratch appear a little darker than the rest of the wood. This only lasts a couple of seconds so I reapply and turn the piece to expose different sections as needed.

Another thing I find helps a LOT to avoid sanding scratches. When sanding with one grit, always sand at 90 degrees to the first direction of sanding. For example, if the work is spinning you hold sandpaper against it, stop the lathe, sand across the sanding path (with the same grit!), then examine with the naphtha. (you can also use alcohol or other solvents but most take longer to dry and some may raise the grain a bit).

Before proceeding, I make sure no scratches are visible from the 1st sanding direction. My theory is that if I can’t get rid of, say, 220 grit cross scratches with 220 grit paper, I’ll never get rid of them with a finer grit!

On some pieces, it’s not practical to sand quite at 90 degrees to the first direction, for example, for coves on spindles. In that case I roll the sandpaper into a small tube to fit, then sand inside the cove an an angle while slowly turning the piece by hand. Sure all this takes more time, but hey,

On flatter surfaces such as platters or the inside and outsides of bowls, I use what I call a “soft sanding block”. I wrap a small piece of paper around a white “magic rub” eraser and sand with medium pressure. The eraser is flexible and conforms to the wood. I should also mention I do very little sanding on bowls, platters, and such - I found that hand scrapers are quicker and gave a smoother surface than sandpaper, especially when sanding with a rotating disk. After hand scraping to remove tool marks, I can often start with 600 or maybe 400 grit. Also, I do almost all my sanding by hand, with the lathe off. For things in chucks I often remove it from the lathe, chuck and all, and mount it in a carving and finishing post from Best Wood Tools. This holds the work in a comfortable position.

JKJ

 

[Brad Campana]

I can’t advise on finishes for anything but straight wood.

I do use a way to find scratches before they are sealed under a finish. I use two things, a small, bright light source on a flexible neck, and Naphtha. I position the fixture so the light is at a glancing angle to a part of the work. I put some naphtha on a small piece of paper towel and apply it to the wood. At first, the liquid soaks in a gives a wonderful preview of what the wood will look like with finish. Then, just as the naphtha starts to evaporate (and it evaporates quickly) I examine the wood under the glancing light. This tends to make any remaining scratches visible since naphtha in the scratch doesn’t dry as fast as on the surface, making the scratch appear a little darker than the rest of the wood. This only lasts a couple of seconds so I reapply and turn the piece to expose different sections as needed.

Another thing I find helps a LOT to avoid sanding scratches. When sanding with one grit, always sand at 90 degrees to the first direction of sanding. For example, if the work is spinning you hold sandpaper against it, stop the lathe, sand across the sanding path (with the same grit!), then examine with the naphtha. (you can also use alcohol or other solvents but most take longer to dry and some may raise the grain a bit).

Before proceeding, I make sure no scratches are visible from the 1st sanding direction. My theory is that if I can’t get rid of, say, 220 grit cross scratches with 220 grit paper, I’ll never get rid of them with a finer grit!

On some pieces, it’s not practical to sand quite at 90 degrees to the first direction, for example, for coves on spindles. In that case I roll the sandpaper into a small tube to fit, then sand inside the cove an an angle while slowly turning the piece by hand. Sure all this takes more time, but hey,

On flatter surfaces such as platters or the inside and outsides of bowls, I use what I call a “soft sanding block”. I wrap a small piece of paper around a white “magic rub” eraser and sand with medium pressure. The eraser is flexible and conforms to the wood. I should also mention I do very little sanding on bowls, platters, and such - I found that hand scrapers are quicker and gave a smoother surface than sandpaper, especially when sanding with a rotating disk. After hand scraping to remove tool marks, I can often start with 600 or maybe 400 grit. Also, I do almost all my sanding by hand, with the lathe off. For things in chucks I often remove it from the lathe, chuck and all, and mount it in a carving and finishing post from Best Wood Tools. This holds the work in a comfortable position.

JKJ

John, thank you for the detailed explanation. I appreciate the time you put into this.

 

[Erik Christensen]

I do a fair number of resin/wood bowls every year and finish coat all of them with clear epoxy. To keep thirsty end grain from sucking up so much finish that a second coat of resin becomes necessary, I apply one or two coats of Osmo Oil as a sealer.... It is much easier to wipe on some penetrating finish and toss the rag than to measure resin/mix/brush/then clean brush with acetone. Don't waste time sanding past 150 as resin is so thick a coating that it hides all scratches (but not tool marks or torn grain). Here is what currently is in the bay window behind the kitchen sink...

 

[Brad Campana]

Thanks Eric for the information. Your bowls look great.