Finishing Detailed Coffee Table Surface


DaveRossi

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A friend and I have built this coffee table. The surface was run through a C&C machine and the Periodic Table of Elements has been carved into the wood. The wood is Mahogany. The deepest cut from the carving is 1/8".  I'm not worried about the staining process. Even if stain pools in the carving a bit it'll hep the letters pop I think.  My real concern is the finishing.  I'm used to using oil-based poly applied with a brush, but I think a brush is impractical with all the detail, and I don't think it pooling in the letters/numbers does me any favors. So I'm thinking spraying is the solution, but I've never sprayed a finish coat.  The opinions are wildly diverse on the subject; dilute/don't dilute, oil-based/water-based, spray/never spray.  I've put a lot of time into this project, and it's a gift for someone. I'd hate for it to fall apart in the finishing stage.

Any suggestions from the collective would be very helpful!

 

Thanks!

IMG_7069.jpg

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First off, that's a truly awesome piece.  The nerd in me is very pleased :)  And I can think of a few science teacher buddies who would kill for that table.

Question though - how did you address expansion for that top?  Is it shop sawn veneer or something?

On finishing:  I agree with Ace.  I would use oil and a glass top.  But if glass top won't fit the aesthetic of the room, then I'd spray lacquer or waterborne poly.  But glass has the added benefit that nobody will ever chip those intricate carvings.  

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Thanks for the kind words.  My hurdle with finishing is that all the furniture in that room is dark, walnut color so I'm trying to match that. As is, it just wont fit in the room aesthetically.  I can get my hands on an HVLP sprayer, but it would be a Wagner/mass market model.

As for expansion, the top is 3 pieces. We used a finger joint router bit, but in hindsight I think dowels would have been easier.

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4 minutes ago, DaveRossi said:

The glass on top is an interesting choice I hadn't considered. Staining will be pretty straight forward, I think I can manage that. It's the finish coat that scares the hell out of me. Maybe glass is the solution. 

I think you've got it backwards :). Staining is much more difficult than applying a finish coat, pretty much regardless of what the topcoat is, IMO. 

Re: expansion - what I was getting at is how did you insure the expansion of the top won't bust apart the legs?  I may be missing something. 

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Nice period(ic) piece! 

I think what everyone is concerned about is whether or not your joinery methods allowed for wood movement. That width of top could expand and contract by as much as 3/8" or so, depending on where you are and the swings in relative humidity. If the ends of the top are glued or otherwise fixed to the cross members, you're in trouble.

As for finishing, I would spray it with lacquer or poly, even if I had to use rattle cans.

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The truth is we did not account for expansion.  I'm in Southern California so it's a fairly arid, stable environment, and (to date) haven't had any issues with other pieces I've made, some of which are 4-5 years old, but I'm sufficiently terrified now haha.  Being somewhat of a novice, how do you allow for movement like that?

As for stain/finish, I'm used to using oil-based on both counts, but maybe water-based is a better choice this time around, and may help apply the finish coat more evenly with a sprayer?  I've never had a problem staining, but that finish coat always finds ways to test me; bristles, bugs, bubble, runs, it's always a challenging step for me for some reason.

Thanks again for all the insight everyone!

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3 hours ago, DaveRossi said:

The truth is we did not account for expansion.  I'm in Southern California so it's a fairly arid, stable environment, and (to date) haven't had any issues with other pieces I've made, some of which are 4-5 years old, but I'm sufficiently terrified now haha.  Being somewhat of a novice, how do you allow for movement like that?

If it were me building this piece, I would probably just make the top overhang all the sides like a traditional table, then attach it to the base using screws in oversized holes to allow for movement.  But if you wanted to stay with the same basic design, you would probably use a frame and panel approach and make the periodic table panel float freely in a frame, so that it can expand and contract within the frame.  

The mahogany looks pretty straight grained, it's certainly possible that in your environment you won't have an issue.  Just keep it in mind in future builds that wood is always going to move, even in a stable environment, and you should account for that in your designs.  

Like I said though, very cool piece.

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15 hours ago, DaveRossi said:

The truth is we did not account for expansion.  I'm in Southern California so it's a fairly arid, stable environment, and (to date) haven't had any issues with other pieces I've made, some of which are 4-5 years old, but I'm sufficiently terrified now haha.  Being somewhat of a novice, how do you allow for movement like that?

As for stain/finish, I'm used to using oil-based on both counts, but maybe water-based is a better choice this time around, and may help apply the finish coat more evenly with a sprayer?  I've never had a problem staining, but that finish coat always finds ways to test me; bristles, bugs, bubble, runs, it's always a challenging step for me for some reason.

Thanks again for all the insight everyone!

Super awesome table. Where in so cal are you?

If you're close enough, you can bring it over to my shop and spray it to your hearts content.

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Thanks Brendon_t for the generous offer! We're in Pasadena at a buddy's shop. We're rigging a space, but failing that, I may take you up on it!  Where in LA are you?

bgreenb, thanks for the insight. This whole project has been quite a learning process. Thanks for continuing the education.  I'll post completed pictures come good or ill!

 

Thanks again everyone!

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