Question about when to finish a box with poly

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Forum topic by christherookie posted 01-14-2019 05:04 PM 723 views 0 times favorited 6 replies Add to Favorites Watch
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144 posts in 4053 days

01-14-2019 05:04 PM

Topic tags/keywords: box poly

I’ve started making creative little boxes for fun – and gifts. I’m trying to do everything in a logical order and I’ve hit a snag. It gets tricky when I want to apply my coats of poly. If I have a lid that sits in a recess, that recess will fill up with poly and therefore not seat correctly. However, completely finishing the wood before hand (before assembly) could mean that any wood exposed after cutting could then need to be finished. For example, if I did dovetails on a box.

Maybe there isn’t a universal answer on the best time or way to apply poly to a box. Maybe it depends on the design of a box. I also don’t want it running down the sides which I can see it doing.

But if you’ve got any suggestions, I’ll take them!

6 replies so far

View therealSteveN's profile


7221 posts in 1580 days

#1 posted 01-15-2019 02:15 AM

I’ll start with I really like General Finishes. The link below is to the question of “what topcoat to use?”

Great video, that goes over what you are wondering about, even if you apply the thoughts to another brand of finish. If you haven’t tried them yet, the newer water based finishes are great, both to use, and in the finished product.

No matter what, if you have 30 minutes in a project, or 10 weeks, but especially the 10 weeks part. Before you finish the project, use scrap from the project, prepped just as you have the project, before putting on any finish, even one where you think you know what to expect.

George telling you what you may see in different finishes.

A thought for you, and your sticking box lid scenario. You can mix Poly with Boiled Linseed Oil, and or Mineral spirits, and any or all of it can go over a wash coat of shellac. I would pass on the BLO part of the mix, but over a coat of well dried Shellac, try a coat or 3 of the Poly MS mixed 50/50 and allow time to dry. When fully dried after that first coat I bust it down with high grit sandpaper, not to take it off, just to take of any nibs created. Then you can recoat, and those usually dry quickly (given a temp of 65* or more) when done again give it a rub down with some high grit paper, or I use a crumpled up brown paper bag a lot. It knocks off any nibs, and smooths down any irregularities. try that on a sample lid, to see if you still aren’t a Poly user, just with a kick.

Good luck.

-- Think safe, be safe

View LittleShaver's profile


727 posts in 1626 days

#2 posted 01-15-2019 03:04 PM

I think you’ll find you have better results if you thin your poly 50% with mineral spirits and wipe it on. Puts on thinner coats and I find it easier to control. It also dries a lot quicker, but you do have to put on a few more coats if you want a heavy buildup.

-- Sawdust Maker

View Gene Howe's profile

Gene Howe

12300 posts in 4435 days

#3 posted 01-15-2019 04:10 PM

I think you ll find you have better results if you thin your poly 50% with mineral spirits and wipe it on. Puts on thinner coats and I find it easier to control. It also dries a lot quicker, but you do have to put on a few more coats if you want a heavy buildup.

- LittleShaver

Agreed. Wiping is one of the best methods I’ve found. Judicially applied rattle can poly is another.
I’ll often use Danish oil mixed with the poly or varnish. Not as a thinner, though. And it’s not a fast drying finish. But, the Watco I use comes in varying shades of brown. Saves a step.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View CaptainKlutz's profile


4127 posts in 2500 days

#4 posted 01-16-2019 06:49 AM

Many ways to do this:
For me any project where there are inside corners or edges that are difficult to properly apply finish once assembled; it is best to finish the inside surfaces before assembly.

Hence, I apply finish before assembly to inside of most every box, cabinet, or even small drawers that I make.

Don’t finish everything, only those surfaces that are hard to reach due small access with big hands, tight corners where finish will pool, or if you complete klutz with paint brush like me.

Yes, masking surfaces/dados/rabbits/trim/etc is no fun and adds to finishing cost; but the stress reduction is worth it to me. For small boxes, helps if learn how to use liquid latex masking and masking putty available from art stores.
Best not forget that also need to mask off the interior finish before final glue up too.

Another part of my finishing schedule for interior finishing work, does not include the final top coat.
Except drawers where I spray all layers of either shellac or WB poly, will usually apply last hand rubbed coating of Arm-R-Seal poly or WB poly after assembly. This allows get good base finish, and yet allow me to fix any glue residue on initial finish, and give the interior a uniform appearance.

Hope this helps.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View MrUnix's profile


8406 posts in 3205 days

#5 posted 01-16-2019 06:54 AM

I always try to account for the finish thickness… so instead of a super tight fit, it will fit a bit loose until the finish goes on. After you have done a couple, you will get an idea of just how ‘loose’ to make it. Sometimes, all you need is a snug fit, and then the final sanding will give you the proper allowance. And as mentioned, a wipe on (50/50 mix) will go on easier and allow for better control of final film thickness.


-- Brad in FL - In Dog I trust... everything else is questionable

View OSU55's profile


2736 posts in 2996 days

#6 posted 01-16-2019 01:34 PM

Agree with above 1:1 poly and ms. For first 2 coats apply like danish oil – apply liberally, keep wet and let it soak in 5-10 min, wipe off. Apply final coats as you wish. This fully seals the wood and makes it easy to apply final coats. Better than sealing with shellac. Shellac has a short open time and doesnt soak in as deeply to seal and is more difficult to apply unless sprayed.

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