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Even Sheen with Poly

16K views 15 replies 11 participants last post by  kdc68  
#1 · (Edited by Moderator)
I'm in the process of finishing a slab of redwood burl. I've put 2 coats of Minwax natural stain on it, and I want to now put several coats of polyurethane on top. I experiemented a bit on the underside of the slab with gloss poly and the sheen was quite uneven. Any tricks to getting a nice even sheen when using poly? I typically use wipe-on poly and sand with 400 grit b/t coats.
Thanks!!
 
#2 ·
If you get an uneven sheen level, it is because the finish is soaking in more in some spots than in others. The best way to avoid this is to have a smooth, non-porous surface before you start. Sometimes that means using a grain filler. Sometimes you just need a lot of coats. The problem is a lot more noticeable with gloss than it is with satin.

I've used a clear grain filler called CrystaLac with good success in the situation you describe.
 
#3 ·
Like Charlie above said, just add more poly.

My method of getting a mirror finish with polyurethane is to apply one coat and let it dry for at least 24 hours as it soaks in and the drying process takes longer. After this first coat I scrape the surface with a single-edge razor blade, watching the gloss on the surface. When the gloss disappears the area is leveled. If, after some scraping, there are still some small areas of gloss left, these are low spots. The low spots need to be filled with more coats of polyurethane, scraping between coats. What you are doing is removing the high spots with scraping and filling up the low spots with polyurethane. When the surface scrapes leaving no gloss spots, the finish is level. At this point you can add one more coat of polyurethane with a brush that has soft bristles like those of an artist's brush and accept the gloss you get with that, or you can rub the surface with OOOO ("four ought") steel wool, the finest there is. After that, wet sand the surface with 600 grit "wet or dry" sandpaper. The object is to remove any lingering scratches. After sanding, use some automotive rubbing compound to rub the finish to a beautiful gloss. A final coat of wax rubbed out helps with the gloss.

Planeman
 
#4 · (Edited by Moderator)
You have to "finish" the finish. Do you process of sanding
between coats and applying finish, cut the final finish back
to level after it has cured (about a month) then sand
and polish it to an even sheen.

I never do this though… too much hassle. It's a reason
I use shellac most of the time.
 
#5 ·
here's my OCD ultra glossy method. I typically put my stain/oil down and then clean it with lemon/orange oil. then i put 1 primer coat of poly down then lightly sand and fix any burn-through and add 3-4 more coats of wipe on before sanding to level it. then i add 1-2 more coats and finish sand and wax everything. the wax will fill the fine scratches and give you a mirror polish that will last for years. biggest thing is to have a very wet rag/paper towel so the wood is nice and sopping with finish otherwise it will take forever. typically it takes me 1-2 days to put a finish down.
 
#10 · (Edited by Moderator)
I think spraying helps with all aspects of finishing. Whether it is building up an even coat, or trying not to remove a stain with the brushing process - spraying offers a solution to all these issues. Wiping poly over oil based stain is particularly problematic because the stain will tend to lift off and streak.
That said, burl wood has its own characteristics that a finish may not be able to alter.

This is Deft brand poly sprayed with a gravity feed HVLP gun.
Image


My biggest complaint with poly is the long dry time. I think the door took 24 hours to cure.
I prefer lacquer whenever possible (except exterior projects).

If a sealer (shellac) was going to help, it probably should be applied before the stain coat.

Best of luck with your project!
 

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#11 ·
You guys need to give scraping with a single-edge razor blade a try! Its faster and better than using sandpaper and it doesn't clog. And single-edge razor blades are around $3 to $5 for a box if 100 from your local hardware store.

Planeman
 
#14 ·
Rob, The problem is due to the early growth being so much softer and more porous than the late growth. The early growth soaks up all the finish while it lays on top of the late growth. I've done a lot of reclaimed redwood and LOTS of coats has been the only fix I've found. I've tried sealing with shellac, etc but I always wind up just applying lots of coats. The thinner the finish the more the early growth soaks it up. It's like finishing a sponge! Just keep laying on finish. I thought I'd never finish the redwood/maple bandsaw box but it finally turned out perfectly. Redwood is not easy but the end result justifies the aggravation.