Painted a routed plywood edge

David Agnew

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Hi guys. I'm here for advice again. :eek: We're in General Q&A because this compasses design, power tools, and finishing.

I'm designing a fireplace mantel/surround for a brick fireplace. It will be painted.

The area above the firebox is a brick arch. I'd like to face above the arch with 1/2" or 3/4" plywood, cut to match the arch. I'd like to route a decorative edge on this arch (cove, round over, beaded, haven't decided). Locally, I can get 3/4" C3 generic Birch (7 ply, I think) and B2 Baltic Birch (11 ply?).

I've never edge routed plywood, nor built something with painted, exposed plys. Am I on the wrong track or could this work? Will the plywood hold the profile ok? Will the paint finish look ok on the routed edge? Is there anything I can do to ensure better results?

Any guidance is much appreciated.
 
My first thought is to make the arch from segmented solid wood like poplar, since you want to paint it. That way, you don't have to be concerned about raw plywood edges.
 
the plywood edge is going to really absorb the paint and be much rougher and will take a lot of work to keep it from looking like a plywood edge. Especially if it is a routed edge which will really show up the layers.

Run a piece of scrap ply through your router table with your chosen profile and then paint it. You will see what I mean. Its not the worst looking thing ever but its certainly not choice. If you are using a simple edge like a round over that can be sanded easily then it isn't as bad after its sealed up.

the idea of using poplar is where I would go.
 
I don't even consider putting a profile on plywood edges. If it is straight (like the top of a cabinet), I glue a hardwood edge on two sides, then trim the ends so the plywood and wood are absolutely even (since you need to trim the plywood anyway to make it smooth enough to glue) and glue hardwood on the other two ends. If it is a curved surface, then for discussion assume I am thinking of 8 sides to make the "circle". Glue hardwood on the sides and end, but they don't have to come to the corners. Then cut off 45 degree corners (both plywood and hardwood), and glue hardwood on the diagonals. Now cut the outline you want in the hardwood, and put whatever profile you want in the hardwood. You will have minimal end grain, so the profiles should cut well and stay nice.

If you use 45 degree cuts (8 sides if you were doing a circle) the hardwood edges need to be fairly wide. If you use more pieces, the width of the hardwood gets a lot narrower. Try drawing it out in pencil on your plywood, and decide how many pieces and how wide you want the hardwood.

C3 Plywood is not very good, even for paint grade. I would go to at least B2. Being near the uneven heat of a fireplace you may appreciate the extra stiffness of the 11 ply Baltic Birch.
 
Thanks for the ideas. Your comments have reinforced my suspicions.

Gluing a multi-segmented hardwood edge is my fallback plan... it will be very time consuming and finicky. It's a last resort.

MDF had not occurred to me at all. That actually sounds promising. Never routed and painted MDF either. Could you guys chime in a little more on that?

Thanks.
 
how severe is the arch? why not run a piece of 1/4" thick bead around it? glued and bradded. first put the two side pieces in then they will hold the radius piece. Thats what I have done when an arch is involved.
if you do want a bigger molding then, yes you are going to have to do a segmented glue up and route it to the radius and profile it. substantially more work unless that is the specified detail.
 
I have only made one thing with mdf. the guy I bought some of my used tools from made a number of things in his home from mdf and painted it. with care mdf looks pretty good painted. in some respects it looks better than wood.

as far as the routed edges go. this guy had an entertainment center and a china hutch with leading mdf edges. it was some profile like an ogee. it looked fine. we talked at length about his work (I am a bit of a talker and question asker. For once he was some one who appreciated that in stead of being annoyed by it lol)

Sealing the mdf, especially the edges is the key.

The one thing I made was for a bedroom set I had (this was more than 20 years ago) I had used 1/4 round to cover the one showing edge but the rest was sealed, I remember multiple coats and good sanding, and then spray painted. I was trying to match the formica type stuff that covered the rest of the set and actually had very good results. unless you got up close it looked like part of the set.

practice with some.
 
You guys have convinced me to re-think. I've discarded the idea of profiling the arch. I think I'd rather stick to something I know. I'll simply tack a stick of moulding onto the bottom and call it good:

di-DOYJ.png


This example is 1/2" plywood rather than 3/4". The corner there on the right is mitered into the wrap piece. The moulding on the bottom is a 7/16" x 3/4" stick of stop moulding from HD. Have to angle cut the one end to fit. The crown is standard 2 5/8". I'm playing around with perhaps a taller ogee w/ dentil, but I'm unsure if it will fit with the style of the room. The shelf is 2" thick. Probably will be a box rather than a slab. Haven't gotten to that detail. Also haven't decided on exact shape/size/detail on the corbels. Will probably NOT be carved. May be raised panel... might not. Might be applied panel... might not. Still brainstorming and looking at photos.

Thanks for the help.
 
the crown looks nice have you considered a large cove? it would follow the look of the arch
possibly a cove and bead which is quite striking imo
 
given what I see in your picture I can see why you wanted to profile the arch. I am guessing you didn't want the profile to just end on each side but I think your new plan will actually work out better.

it looks nice.
 
I'll have to move this to Design soon....

Large images. With cove. I agree, that's a VERY sleek look. Objectively, I really like it, but I'm not sure it'll fit the room. I've added a little more detail to the model, showing the faux finished walls, fireplace details... Comparison between colonial crown and a plain cove. And an overall shot. Room to the right is kitchen.

di-YW1B.png


di-6ONB.png
 
Personally, I prefer the cove for its sleeker look. But I lean toward clean and simple more than ornate and complex.
 
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