Sealant Test

I’m in the process of designing a couple projects that will come into contact with water, so I looked through the forums on what other folks have used, went to the local hardware store, dropped some money on a bag full of sealants/finishes, and decided to give them all a try. Since it looks like there isn’t too much information on how proofgrade materials look with stuff coated on them I thought I’d share what I found out.

First I cut a bunch of (about) 1" by 1" standard test designs on the proofgrade draftboard and maple hardwood I got with my GF. These designs have both levels of scoring and etching from the GF app, as well as a small hole cut into the top. I then applied the following on the design:

1 - nothing (control)
2 - Minwax water based polycrylic, 1 coat
3 - Minwax oil based fast drying polyurethane, 1 coat
4 - Howard cutting board oil

And here are the results. Draftboard is on top and maple hardwood is on the bottom:

So yeah, the draftboard just soaked that butcher block oil (4) right in. And the oil based polyurethane (3) too to a lesser extent. The polycrylic (2) looks nice on the draftboard, but it has a really rough texture. It may just be me not applying it correctly? Hopefully it’ll improve after I sand it down a little and toss on another coat because it’s the only finishing that preserves (most of) the scoring contrast on the draftboard.

As for the maple hardwood I honestly didn’t expect too much of the finishing to stick because the wood was already finished. But it definitely worked. I don’t like the way the polycrylic (2) looks on finished maple but the polyurethane (3) and butcher block oil (4) look good—the 4th one looks better in person than on camera—and I can both feel a difference between them and the control and see that they reflect light differently. I’d say the polyurethane one is even shiny.

Next week I’ll put a second coat on all these samples, do the same on maple plywood once I get them in, and update with some better pictures during the day. And then once I get the backs coated as well I’m planning on doing some submersion tests as well.

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Thanks for doing these tests! I look forward to seeing the update when you complete them. It will be especially useful to have a good method for sealing Draftboard. I made a little lawn ornament (search for Uncle Fester) out of draft board and sealed it with several coats of Liquitex matte acrylic varnish, put it out on the patch of new sod where it has been watered every day for about a month. It has suffered severe water damage so that clearly was not sufficient.

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I have used the polycrylic in finishing hand rails, drawer faces, butcher block top to my standing desk etc. Sanding definitely makes a difference. After 3 coats it gets silky. I have used it on engraves in proofgrade that will be painted. The end grain pores in the veneer are opened by the engrave and capillary action will have the paint bleed into them. Seal first, then pigment.

Edit; Wet sanding between coats with 600 wet or dry paper.

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Okay that is super helpful! I just saw someone do some laser cut painted ornaments today and am going to make some and it’s helpful to know which step comes first. :slight_smile:

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I can’t wait for the water tests. I’m glad you’re doing this so I don’t have to. I’m far too lazy.

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I use 220 to sand the first 2 coats to a dull finish, then if I’m looking for a satin finish, I’ll sand with 800 grit or “Used 400” grit, and use danish oil, or lemon oil as a lubricant.

(Used 400 grit is made by rubbing the abrasive sides of 2 sheets 400grit together) It cuts fast, but not as deep or as quick as fresh 400.

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I use a mix of Shellac (Bulls-eye) and denatured alcohol. My first coats are 50/50 and the last coat is 75/25 (shellac/alcohol). I’ll put a half-dozen coats on because they go on fast & dry within about 10 or 15 minutes.

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This is terrific! @jamesdhatch I’m a big fan of shellac, but it clouds and then dissolves with exposure to water, as I recall.

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I was out of town this past weekend so have only been able to add one more coat. Here they are with two coats!

IMG_20171016_181848330

The polycrylic (2) on draftboard definitely became smoother after a second coating. The coat is kinda bad but that’s more because of the bad sanding job than the finish itself—I only had 150 grit sandpaper in my house so yeah not the best thing for the job. The oil based polyurethane (3) got a little rougher on the draftboard though.

Of all the draftboard tests the butcher block oil (4) simply feels the best. It still feels great on the maple hardwood but it gave the scoring a smudge effect that I’m not too big of a fan of. I think the polyurethane looks the best on maple at this point.

I think at this point I’m going to start coating the back and then do some water tests. I am excited to see how badly the uncoated draftboard do in water…


Side note / question: when updating a thread should I add to the original post or post as reply?

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As replies!

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Well now I’ll have to test that :slight_smile:️ Fortunately I keep it in a squirt bottle (really - quick & easy to mix & dispense and then wipe out with a foam brush). I should be able to get a couple of coats on tonight.

Thank you!

Okay that took a while (forum says 12 days) but I finally finished coating everything and got a chance to dump some proofgrade into water…

First, here’s what they look like before any water. From top to bottom we have pg draftboard, pg maple hard wood, and pg maple plywood. From left to right we have “control” (just cut, no finishing), 2 coats of polycrylic, 2 coats of polyurethane, and 2 coats of mineral oil.

There are smudges on the control draftboard because the it soaks up everything and my fingers weren’t clean when I handled it. The polycrylic gave a slight resistance / stickiness to all three woods. The polyurethane was rough on the draftboard (probably an application error really) but was nice and smooth over the finishes of the maples. The butcher block oil made everything a little more slippery.

The following is a “splash test” where I put all the pieces in a baking dish, poured half a glass of water on them, pulled them out immediately and dried them on paper towels. Sort of to simulate a “oops I spilled a drink on my coaster” situation.

Nothing looks too different but the control draftboard and oiled draftboard definitely felt different. They soaked up a lot / a bit of water respectively. I couldn’t actually dry the control draftboard out completely with paper towels. So note to self: don’t use draftboard for coasters unless you plan on putting some finish on it.

Here’s what happens after I “submerged” them in water for five minutes. I put quotes around submerged because wood floats. So I basically stood there and just kept gently pushing them underwater. Well, except for the butcher block oil draftboard because that one just sank.

I expected more excitement but… nothing exciting happened? The uncoated and oiled draftboards soaked up even more water. The polycrilic draftboard looked a little worse to wear and you can see the fibers. But honestly the water just came off all the other ones with a few pats of a paper towel. A little bit of burnt carbon came off of the unfinished edges of the maple ply when I rubbed it dry, but that’s pretty much it.

Gonna leave all these things floating upside down (except for the one that sank) overnight and see how they look tomorrow…

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Wow it’s been over 2 weeks since I posted the last one promising an update. My GF had to be warranty replaced in the meantime so I have not had the time to think too much about GF stuff that isn’t yelling at UPS.

I forgot to take photos of the results of the submersion test, but the conclusion is that the controls and ones covered in cutting board oil very definitely soaked up water overnight and curled up a lot—especially the hardwood. Not surprising at all! Everything else did, too, but to a lesser degree.

After drying over the next day on a paper towel, the hardwood ones remained slightly curled. The plywood you couldn’t tell got wet at all—even the control. The draftboard definitely did not look pretty as you would expect.

So lesson here is to use plywood for things that will get a bit wet and if you’re going to immediately dry it off don’t bother with finishing the edges. At least that’s my takeaway.

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I did about 4 layers of spray Thompson Water Seal on draftboard, and the water beads right off! I wouldn’t soak it, but for dew I think it’ll be ok.
It darkened it, but only a few shades

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