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I'm doing to hobby pieces using 3/4" pine ply.

On my faces, I've sanded with 80, then 120, then finish with 220 using random orbit sander.

To the touch, it's very very smooth. I'll give it a good wipe down to get rid of all the dust.

I'm staining with some red mahogany using a stain rag. I let it sit about 12 hours. It still feels pretty smooth.

I then will add, one coat at a time, oil based polyurethane.

When that dries, its gritty ... even after the 3-4 coat.

I'm looking for a REALLY smooth and glossy finish.

How do I achieve this? I thought one wasn't supposed to sand after a poly coat. Do I need to sand in between poly coats?

OR ... should I be using a different finish? I'd like it to be sealed so if a drink or something is placed on it, the wood will be safe.

Any help is appreciated!

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Have you considered "sanding the finish"? Here's the basic idea:

  1. Let the finish fully cure. This usually takes a couple of weeks. You will know it's fully cured when you sniff it and can't smell the finish.
  2. Sand with an abrasive, such as 0000 steel wool. This will create a finish smooth to the touch, but will dull the sheen. That may be what you want (if you're looking for a matte finish). If you want more glossy, follow the next steps:
  3. Get some wet/dry sandpaper in various grits (starting at 600 and up to 2000, depending on the level of gloss). Back the sandpaper with something flat and wet the finish in soapy water, then sand. Every once in a while, wipe of the wetness, dry it, and look for a consistent sheen. Keep going until everything is shining the same amount.
  4. Keep going until you get the shininess you want.
  5. Finish it off with a coat of wax.

The hardest part is getting a consistent sheen between coats. It's nearly impossible if your wood isn't flat, but since you're building with plywood, it should be easy.

That's how I used to finish all my projects, but lately I've become a fan of a much thinner finish. I use wipe-on poly (which is just full strength poly diluted with mineral spirits). I wipe it on and gradually build a finish, but stop before it gets "plasticky." Finally, rub the finish with a paper bag; there's enough abrasive that it will smooth things out without ruining the sheen.

This is all detailed in flexner on finishing. That's probably the "bible" of finishing and a fantastic read.

Good luck!

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When that dries, its gritty ... even after the 3-4 coat.

This is likely because the first coat of finish caused some roughness to emerge1, referred to as 'raised grain', and you didn't tackle it then. When this happens you need to sand after the first coat of finish has dried enough that it's easily sandable (about a day, sometimes less and sometimes more) to remove any of this initial roughness.

You can submerge any roughness of this kind if you just apply enough finish, sometimes referred to as "burying the raised grain", but this may require perhaps 6-8 coats of oil-based varnish applied at full strength with a brush so it's quite a commitment in terms of amount of finish and time needed with oil-based varnishes.

I'm looking for a REALLY smooth and glossy finish.

You could probably do with what's variously called 'perfecting the finish', see this previous Q&A, Leveling a finish/finishing the finish. Also see How do I achieve a "piano black" high gloss finish on wood? for further related info. Do note that generally this process requires the finish to be fully cured, so a wait of at minimum two weeks to as much as a month after the last coat of varnish is applied (some wait longer than a month, just to be on the safe side).

Depending on just how smooth you mean, you may also need to use grain fillers or pore fillers (often the same type of thing) for a completely smooth finish on some species. Anything with coarser or more open grain can really benefit from filling, the oaks are maybe the best examples but also ash and chestnut, and to a lesser extent the various substitutes for mahogany and black walnut. You don't need to use grain fillers on any softwoods (no pores), or on tight-grained/close-grained species like maple, beech, cherry or poplar.

Note: if you are grain filling you generally do this after the wood is stained, with a filler colour matched to the stained and finished colour of the wood, or a tad darker.

I thought one wasn't supposed to sand after a poly coat. Do I need to sand in between poly coats?

Sanding after the second coat of finish is a slightly contentious issue as many finish manufacturers recommend it, or state it's necessary, and numerous woodworking gurus do it and suggest it's needed, but of course you don't sand anything unless you need to sand it, and the simple truth is sometimes you don't need to sand between coats of finish..... in fact you can substitute often for sometimes here although how you apply the finish and how clean the drying conditions are (i.e. little or no airborne dust) are important factors. See Issue sanding between coats of polyurethane for more.

OR ... should I be using a different finish?

A smooth finish can be achieved faster, but with much more effort, using French polishing which is a traditional method where you rub on shellac. Once they see the (considerable) effort needed to apply shellac this way most people look elsewhere2.

Depending on the project you could try spray lacquer, which is a very fast-drying finish like shellac. But only small projects are really practical to finish using lacquer from spraycans, anything fairly big really require a spray setup (compressor and spraygun).

I'd like it to be sealed so if a drink or something is placed on it, the wood will be safe.

In terms of consumer-level finishes that are widely applicable to furniture work oil-based poly is about the best for waterproofing, in addition to providing the best scratch-resistance. It's also cheap, available everywhere and is easy to apply to a high standard. These are all reasons why finishing guru Bob Flexner, among others, recommends it so highly.


1 The first coat of most finishes cause a slight roughness to arise on wood that has been smoothed by sanding (can be seen less after scraping, and particularly after planing} although waterbased finishes are by far the worst offenders for this.

2 Plus it's also not very waterproof and easily damaged by any alcohol, which discounts it for many furniture projects in the modern home.

  • One thing we did in woodshop was wet down the pieces to be finished with water, let them dry overnight, and then sanded the grain that had been raised. This seemed to minimize that amount that raised when the first coat of finish was applied. Of course this might not be practical depending on the size of the items. – martineau Jan 10 at 16:32
  • @martineau, yes pre-raising the grain is an optional preparation step that is often done. Some craftsmen for certain types of project will do this twice or even more, although some others scoff at the practice it is definitely necessary to do it more than once sometimes to get the wood to stop responding to further wetting. – Graphus Jan 10 at 22:02

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