[ChocolateThunder]

Big walnut slab destined for my entryway as a bench. I laid down a thorough coat of Watco Danish Oil (yes, yes, applied correctly, dried and cured for 3 weeks, looked awesome), and being happy with the appearance but not durability, I decided I would fill the pores to improve the appearance of the urethane finish I was planning for (at the time was Arm-R-Seal satin which I thought looked kinda weird over the open pore structure; this was before I changed the plan from ARS to Enduro-Var II since it comes in flat, which was my original preference since it doesn't look as bad over irregularly-grainy surfaces).
I applied Aqua Coat Clear Grain Filler as instructed, 3 coats, sufficient dry-time, after which I applied a thin coat of Enduro-Var II flat. It was then that I noticed that the Aqua Coat was not clear as much as it was a light brown - something I noticed when I was applying/scraping/squeegeeing it along the slab surface. Based on previous tests I thought it would still dry clear (I was wrong). So now I have a smooth flat surface with a water-based urethane covering what appear to be dust-filled pores in an otherwise lovely piece of walnut. Bummer.
So, how do I remove the Aqua Coat from the pores? Any recommendations on strippers, or am I destined to be the new owner of an electric hand-planer, or test how flat I can keep the surface while sanding 1/32-1/16" off with my 6" ROS 60 grit? I don't think removing the single coat of EVII will be difficult since it was applied to a pore-filled flat surface - I'm more worried about how to get tainted grain filler out without having to remove all that wood...

I really appreciate any input. And if it does come down to taking the wood down a bit, advice on how best to do that (short of replaning) would be appreciated.

 

[CaptainKlutz]

Comments FWIW:

- Aqua clear is a shellac based clear filler containing alcohol/glycol. The brown color noticed applying grain filler and the dark brown of pictures makes me think you used dark brown Watco Danish oil; and experienced drag out. If true, the 3 days was not long enough cure time.

- Enduro-var is a alcohol/glycol containing WB finish, and will soften/remove the Aqua coat grain filler. The white residue is a likely a reaction of the 2 products.

- There is a chance the Watco sealed the grain, and you might be able to use xylene to remove the EnduroVar and alcohol to remove the filler, maybe? With cost of solvent and PPE for the clean up; it won't be cheap fix.

- IME - Only way to fully clean filler from wood pores is chemical dip tank, or a wide belt sander. 10 minutes rented on commercial wide belt sander is usually cheaper.

My colored walnut schedule is:

• Grain fill with Behlen's neutral water based grain filler (absorbs dye stain well), or Aqua coat if only using clear top coat and NO color.
• Color with diluted NGR dye stain - either Mohawk Ultra Penetrating, Behlen's Solarlux, or Transtint mixed into acetone/alcohol solvent blend.
• If applying a WB top coat, spray the first layer of top coat to lock down color. If using WB top coat with a brush, spray on 1lb cut of shellac to lock down the color, or the color can smear with brush. Any oil based top coat can be applied on NGR dye stain without a sealer step, even wiping on ARS.

If don't need a lot of color in walnut: Ruby/Garnet shellac used as a sealer works well to make it darker/richer looking. But only when not using grain filler.

PS - Always test your finish schedule on scraps, not a project.

Best Luck.

 

[ChocolateThunder]

CK - thanks for the reply!
I used Watco "natural" DO - not any tinted version. And I let it cure for 3 weeks, not 3 days.
Aqua Coat said that their product might have led to some softening of the otherwise-cured DO, and scraping might have removed some wood/DO mix which tinted the AC brown. My theory was that I was simply mechanically scraping up the wood/DO, but chemical breakdown would make sense as I used plastic scrapers mostly. Knowing I had no interest in staining the wood, I wanted to bring out the color of the wood with a penetrating finish applied before AC since I know AC would block that finish where it was filling pores.
I am hopeful that Xylene + denatured alcohol will strip, thought I might just sand the thin, flat coat of Enduro-Var II off and just try to strip the AC with DA.
Regardless of how I end up removing the AC failure, I am experimenting with other finishes. My original approach was Arm-R-Seal satin 3 thin coats (2 left moist with a wiping from lint-free paper towel, final coat wiped thin but left wetter than moist with the applicator pad) over DO, but I didn't like the appearance of satin ARS over open-pore walnut, and based on input from Bob Flexner's book, felt that pore filling would improve that appearance. I then found EVII flat, and think I like that (but had already pore-filled by this point). I applied EVII, but as in the original post pictures, we all know how that turned out.
Since General Finishes says you can apply water over oil base finishes after 72 hours (if it's a GF product), I decided to give Seal-A-Cell a try as a penetrating finish, and did 2 coats as instructed on a portion of the underside of the slab. I followed this with 3 coats of EVII after only 24 hours of dry time for SAC, just to see if I could get away with it, but it looks cloudy. I'm currently waiting for the 72 hour mark before applying more EVII over another portion of the SAC to see if extended dry time improves the appearance of EVII flat.
It's worth noting that I wasn't as impressed with the SAC (a GF-proclaimed "DO") as I thought I would be. So I'm reapplying SAC like I would/did the Watco DO - 15 minutes, wipe, dry. Reapply 2 more times. We'll see.
I'm also experimenting with a couple other things, to see if I can get that "close to wood" finish in a way that's more durable than Watco DO:

• ARS satin x15 minutes, wiped to moist, allowed to dry (no "left wet" applications to keep it close to the wood)
• ARS mixed 3:1 with 100% tung oil, same application as above.
• ARS mixed with TO and mineral spirits (1:1:1), same application as above.

I am currently on coat 3 of the above strategies, and note that everything, even the SAC that I wasn't super stoked with looks better than ARS on bare wood. They all bring the color/grain out more than ARS satin. Turns out that the Internet was wrong on that one. The ARS doesn't look bad, but there is an obvious difference. The ARS+TO dries slowly and looks great. The 1:1:1 dries quickly and is tied for the lead in appearance with the ARS+TO. The real test will be the durability after I get a sufficient # of coats applied (enough to create durability, but not so much that I get that plasticky finish that is most certainly not "close to wood").

 

[CaptainKlutz]

- EnduroVar is not a durable top coat. ARS is more durable, but need a thick film to provide lasting protection. And none of the single part top coats are as durable as conversion varnish, or catalyzed polyurethane. If you want a thin film build to avoid plastic look, then you need to spray on a commercial 2 part finish so you can control the film build precisely. TBH - Even a conventional SW pre-cat CAB lacquer is more durable than EnduroVar.

- Finishing walnut drives me nuts,
Walnut has fairly large grain, and it you want a smooth flat surface; then must grain fill. The challenge is filling grain AND keeping the color. For air dried walnut, Aqua coat or similar clear filler works well; with an oil based clear coat to add amber to improve richness. But color still fades out over time. Between the challenges of putting color back into commercial steamed walnut, and the brown color fades easily with UV exposure; I find it impossible to keep a rich dark brown in walnut for more than couple years without using a walnut dye stain. The dye stain will not fade as easily, or as quickly as raw wood; and seems to be protected by UV blockers in many top coats. Another challenge is that WB finishes add no amber color, or warmth; making it harder to add richness usually created by oil based top coat. Since oil based top coats are less effective at improving color with grain sealer; the few times I have tested a WB top coat on walnut: dye stain was mandatory to achieve the classic dark rich walnut colors. Hence, the schedule above, and fact I ALWAYS color walnut with diluted dye stain; unless I am using garnet/ruby shellac as the top coat.

The most durable WB finishes I have tested are new polyurethane resins from Italy, sold by; Renner, Milesi, and ILVA. Renner 851 product with optional catalyst is some of hardest WW finish I have seen. It rivals automotive clear coats for durability, which it should, since it uses the same chemistry as newest WB automotive finishes. It is one of the few low sheen top coats that does not change sheen due contact wear, as it does not wear easily. Dare you to rub some paper on satin EnduroVar and not leave a shiny spot behind? Renner 851 barely scratches using garnet sand paper. Have to use aggressive zirconia grits to sand it smooth, if you wait too long to fix blemishes.

As with all finishing discussions, above is based on my experience, and YMMV.

 

[splintergroup]

I use the AquaCoat on walnut frequently. I always apply it to the raw wood after doing a through cleaning of all dust from the pores (I use a small nozzle on compressed air followed by a wipe of mineral spirits). Let the MS dry and apply AC. let dry, scrape/sand, clean, re-apply, repeat until the pores are filled to your requirements.
It is then that I'll apply a finish. Oil, shellac, etc. seem to go past (or around) the AC and don't leave light spots.
Of course the Captain's advice on trying first on scrap is rule #1.

 

[ChocolateThunder]

CK - Yeah, I saw that GF calls EVII "medium durability" and ARS "highest" - I was hopeful since EVII earns a higher hardness rating (123 vs. 77), and has decent water (3 vs. 5) and chemical resistance (84 vs. 99). My current plan is to decide how I'd like to enrich the bare wood (currently thinking either Seal-A-Cell or my homemade DO), followed by wet-sanding a couple coats of something with a bit of tung oil (either my DO or an ARS-TO combo), followed by a top coat. I was thinking if I don't use an ARS-containing wet-sanding approach that I should throw a couple coats of ARS down, let those dry for 3-4 days each, and then 1 coat of EVII flat on top for the lack of reflectivity I'm looking for. Now, I imagine that will mean that the top coat of EVII will be prone to whatever failings that the ARS has but EVII lacks, but I figure having the ARS beneath will protect the wood, even if the EVII fails.
Now, I love the idea of a better flat finish like Renner 851, but I fear that one has to spray that on. I do not have a spray setup (though I do have a compressor suitable, and do have a setup to spray paint), but that Renner sounds like what I need. Do you think I could apply it without spraying? If not, can you suggest a flat/matte finish (OB or WB) that is similarly durable? I'd use ARS but I don't like the satin look, especially with unfilled grain.
SG - maybe I need to give AC a second chance, and just spread it through one spot and discard remainder (or scrape after drying as you suggest) in order to avoid browning. I did and do use a compressor to clean out grain.
I do enjoy the fact that I can experiment all I want on the underside of the bench since it will never see the light of day.

I did sand off the EVII over the failed AC on the underside, and the alcohol didn't remove much of anything as far as I can tell. I'm confident the single layer of EVII was sanded off, so I didn't go the Xylene route. Any other suggestions before I resort to a different chemical stripper (I really don't want to use MC if I can help it), or even go the rough of mechanical removal? And if the latter, any further opinions on sanding with ROS vs. a handheld electric planer?