Finishing African Mahogany counter top

[Jeff Scozzafava]

I glued up boards for a counter top... and just had them run through a large belt sander at a local shop and have very nice 1-1/2" tops ready to finish. They used 60 grit to get close to 1-1/2" and remove surface imperfections then finished with a couple passes at 80.

I know I need to go finer by hand before I use the General Finishes Dark Brown Dye stain... followed by three coats of GF High Performance Satin.

I have a Bosch ROS20VS. Is a ROS right for this? I assume I should be going over the entire surface lightly in a progression from 120, 180 and ending with 220? Followed by vac, microfiber wipe, blow with air... then stain? Should I use distilled water to raise the grain before 120, in between grits or after 220?

Since the top is 5ft x 2ft my plan is to spray the dye stain onto the top to get it on quickly and uniformly... then wipe it off with staining rag. Let it dry a couple days, and then spray the High performance Satin coats. I plan to test this finishing process on the bottom of the counter top first... since I want to seal all sides anyway.

Would it be better to do the last sanding at 220 by hand with a Prepp'in Weapon sanding block in the direction of the grain only to keep the ROS from creating cross grain marks that the dye may accentuate?

This is my first time finishing a counter top... is there anything i am missing or doing wrong?

Thank you for your expert advice for a novice...

[John C Cox]

The most difficult will be going from the machine's 60/80 to your next grit up. You will have to chase all the lines and tracks left behind by their big power machine. Luckily Mahogany isn't bad to sand out....

With this first levelling operation - the big challenge is to get rid of all machine tracks without dishing the top or making it wavy... That's the danger of a ROS... But it's doable. This is also where you will find out about any troubles with end snipe...

I would start with a work lamp shining across the piece at a low angle in otherwise dim light to see the tracks. Try out 120. See how bad the tracks are... If they are deep - you may be better off levelling the tracks back out with good high quality 60 or 80 grit PSA roll paper on a 4' length of good, straight 2x4 or an air file...

If you have to go this route - start crossgrain, move to 45 degrees left, 45 degrees right, then long grain last. Watch the edges - as you can blow your edges in a hurry.

[andy bessette]

I would use a sanding block and not go finer than 180, except perhaps between top coats. Also, after a sealer coat, I would use filler stain, applied with a rag, and wiped off after a short drying time.

[Jeff Scozzafava]

Thanks, Guys.

Andy, you are suggesting a sealer coat on raw wood? I am using a dye, and I don't think it will work if the wood is sealed.

John, is there any ROS trick other than keep it moving and don't let it sit in one spot too long? Would I be better off using a block? Good exercise!

[andy bessette]

...Andy, you are suggesting a sealer coat on raw wood? I am using a dye...

I am recommending a sealer coat before applying filler stain (not dye) because that is what I was taught was required by mahogany.

[Jeff Scozzafava]

Ahhh... yes, I have seen that used for a nice smooth finish. I did a sample piece and kind of like the texture when finished with a few coats of poly on top of the dye. Going next to a stone fireplace and similar mantle in African Mahogany, so I think it works well... if I were doing a piece of furniture, then I would probably go toward the filler.

[John TenEyck]

If your countertop is going to be exposed to liquids, especially anything with alcohol, or will have hot dishes set on it, I would not use GF's HP Poly as it has poor performance in both those regards. EnduroVar would be a much better choice; doesn't spray quite as easily, still not bad, and is far more chemically durable and heat resistant.

As for prep, I usually find it best to start at the finest grit used in my drum sander, sometimes even one coarser, to get rid of those scratches. So if my drum sander has 120 grit on the back roll, I start at 120 grit and go back to 100 grit if the scratches aren't removed in a couple of passes. With African mahogany, I wouldn't go any finer than 150 or 180 grit. Also, I've found no need to hand sand and find it's worse to do so on a face frame, but that doesn't apply here. Anyway, most often, I only hand sand between coats of finish these days. But only you can determine if your ROS sands as well as you can by hand. Mine is better.

I would raise the grain after the last grit, then hand sand the whiskers off with 220. Might do it twice. Then no sanding until after at least the first coat of your topcoat. I normally use 400 or 600 grit for scuff sanding between finish coats.



John

[Jeff Scozzafava]

Great! Thanks, John!

No liquids for these tops... but my next project is refinishing the kitchen table, so I will file that tip away and look at EnduroVar for that...

[Julie Moriarty]

I sprayed a few gallons of Endurovar on a cabinet job I did (Honduran mahogany and sapele) and found it easy to use. I contacted General Finishes about using it on a counter top and they advised against it. They recommended Enduro Conversion Varnish. It's for "high-use projects that receive a lot of wear, such as bars, commercial tabletops, bathroom vanities, around dishwashers, kitchen cupboards or high-moisture areas." I decided to go with Minwax floor poly in satin.

Dying African mahogany is iffy. I've sampled Trans Tint dyes on different pieces of AM with differing results. The dye did well on the sap wood pieces but on the densest heartwood, well, I wasn't impressed. Varnishes with an amber tint to them can give AM a richer appearance. Orange dye in the varnish can bring that rich appearance out more noticeably.

For our countertops, I sanded to 220 before going to finish. I added about 40 drops of orange to a quart of the Minwax floor varnish. Brushed on three coats, sanding 220 in between. Then sanded away the remaining brush marks then wiped on three coats of Minwax Wiping Poly. Each wipe coat revealed brush marks I missed. I first sanded to 220 during the wiping phase then moved to 320 before the last coat. You could also add the use of 0000 steel wool after sanding and before the next coat. Just make sure to remove the steel dust residue.

[Jeff Scozzafava]

Thanks. This brings up a good point... the sample of wood I got a few weeks back was a bit more pink than the full boards I got to make the tops. The GF Dark Brown dye is slightly more black/brown on this wood than the sample... If I want to get more of the "Mahogany Brown" look like the GF stain color... I am trying to figure out which of the red tint GF dyes I can mix with the dark brown dye to get that mahogany red shade in the brown... and how much.

[John TenEyck]

Thanks. This brings up a good point... the sample of wood I got a few weeks back was a bit more pink than the full boards I got to make the tops. The GF Dark Brown dye is slightly more black/brown on this wood than the sample... If I want to get more of the "Mahogany Brown" look like the GF stain color... I am trying to figure out which of the red tint GF dyes I can mix with the dark brown dye to get that mahogany red shade in the brown... and how much.

Try Transtint Brown Mahogany, then add some Dark Brown to it, or the other way around if you need more dark brown than red.

John