Opinions on finish for a plywood workbench top?

[zorkmids]

I'm building a few new workbenches that will have plywood tops. Other than putting an esd mat down, would you finish the top in any particular way?

I'm considering just a polyurethane coat, but would paint be better? Should I even coat it at all and instead put down a sheet of MDF instead?

[tautech]

Add any quick sealing coat then contact adhesive down some Formica laminate or flooring vinyl.
If you find contact difficult to manage, some flooring adhesives might be easier to work with.

[nfmax]

Use MARINE polyurethane varnish, nothing else comes close. If you are really serious, use a 2-pot system. You will never get it off!

[zorkmids]

Add any quick sealing coat then contact adhesive down some Formica laminate or flooring vinyl.
If you find contact difficult to manage, some flooring adhesives might be easier to work with.

Sounds pretty nice. Are you suggesting this specific option because of durability?

[Benta]

Regardless of what you do, seal both sides of the plywood at the same time (unless it's extraordinarily thick). Otherwise it will hang.

[CharlieEcho]

If you want to get serious about it, and the ESD mat area won't be covering the whole table, you can get laminate, epoxy resin or phenolic compound lab table/counter tops instead of finishing the plywood and just fasten them.

Googling around will find a few different manufacturers and trade names for their finishes but it's all reasonably similar stuff. 

[rbm]

If you're going to use a polyurethane finish or 2-part that will seal the wood, then cover both sides of the tabletop with the finish. If you just do the work surface and leave the underside bare (because you don't see it), then the table top could warp due to difference in water absorption / release rate between one side and the other.

[phil from seattle]

Agree on the marine varnish.  I'd also use MDF. While not as strong as plywood, it will be a lot smoother.  Alternatively, you could use something like 1/8" tempered hardboard on top of plywood.  I have it on my bench and it's pretty tough and smooth.

A laminate like Formica works well but it takes more effort to get right. I have an outfeed table in my shop that delaminated after a few years.  Not sure what I did wrong as I followed the directions pretty closely.

[Gyro]

You could try a few coats of Danish oil. It penetrates well and is quite protective (and no hassle with brush marks). The good bit is that you can simply lightly sand and reapply to any damaged areas.

WARNING: Most of the finishes mentioned here involve flammable solvents of one type or another. They need plenty of time to evaporate before you go near them with anything hot - particularly on a flat horizontal sheet!

[CharlieEcho]

If your typical fake-woodgrain formica is acceptable I might check educational furniture wholesalers or liquidators. Tops can always be detached from their existing bases and re-mounted.

[tautech]

Add any quick sealing coat then contact adhesive down some Formica laminate or flooring vinyl.
If you find contact difficult to manage, some flooring adhesives might be easier to work with.

Sounds pretty nice. Are you suggesting this specific option because of durability?

I have benches with both, they each have advantages. Formica is pretty hard wearing and cleans up well but might be too slippery for some. Commercial grade flooring vinyl is non-textured like some domestic grades but not slippery unless polished.
If you're gunna use an ESD mat as well, just use what you like the look of.

I have a mate that does flooring and there's always some 'left overs' in his shop. Your local one will have some for sure and likely can be swapped for some beer which at the end of the day will be cheaper than any varnish that you might have to buy.

[ez24]

Glidden Floor paint

After watching it for years on my porch (no peal no fade) - I started using it for everything, inside and out.  It is also a primer.  I use it on my walls in my house and in a condo I rent (every room).  I use it on workbenches, shelves and used it for murals that I painted on my garage and 4x6 ft outdoor paintings.  Painted the outside of my house 15 years ago and it looks like it was just painted.

Dark colors are tricky to use. 

Saves a LOT of money.  If I do not like a color it becomes the primer for the next color.  And for 20 years I have never thrown out one ounce of paint.   If I pick up an unlabeled can of paint, I know what it is.

[oldnewb]

I prefer a thin sheet of hardboard (AKA HDF, Masonite, etc.) on the top of my workbenches.  It can be glued down with contact cement.  The hardboard is smoother, a bit softer than a plywood surface, and dirt cheap.  If it gets beat up, it can be replaced (although my current bench is nearly 10 years old and still in great shape).

https://en.wikipedia.org/wiki/Hardboard

[Paul Moir]

On my favourite mechanical bench, I simply filled the top and edges of the plywood with (I think) Bondo before painting.  It turned out really nice:  not ultra-hard like formica.  And a good use was found for Bondo!
Marine paint = good paint usually.

[zorkmids]

Regardless of what you do, seal both sides of the plywood at the same time (unless it's extraordinarily thick). Otherwise it will hang.

If you're going to use a polyurethane finish or 2-part that will seal the wood, then cover both sides of the tabletop with the finish. If you just do the work surface and leave the underside bare (because you don't see it), then the table top could warp due to difference in water absorption / release rate between one side and the other.

I've already built the top with two pieces of 3/4" plywood glued and screwed together to make a 1-1/2" thick slab. I'm assuming that means I don't have to worry about finishing both sides like you're both mentioning?

[zorkmids]

I prefer a thin sheet of hardboard (AKA HDF, Masonite, etc.) on the top of my workbenches.

Define "thin" - 1/4"?

[BradC]

I prefer a thin sheet of hardboard (AKA HDF, Masonite, etc.) on the top of my workbenches.  It can be glued down with contact cement.

I use Masonite on all my benches except I hold it down with pin head tacks, that way when it needs replacing its easy to remove. I haven't had to replace mine either, but if I do it's not difficult.

[Cerebus]

You could try a few coats of Danish oil. It penetrates well and is quite protective (and no hassle with brush marks). The good bit is that you can simply lightly sand and reapply to any damaged areas.

WARNING: Most of the finishes mentioned here involve flammable solvents of one type or another. They need plenty of time to evaporate before you go near them with anything hot - particularly on a flat horizontal sheet!

I'd second that, but say go for neat tung oil instead of Danish oil. Tung oil is one of the components of most Danish oil mixes (along with Linseed oil and other drying* oils). Tung is the most water resistant and chemical resistant of all the drying oils. It used to be used as the finish for laboratory benches. A small bottle goes a long way.

It's a little bit more of a effort to apply than Danish oil, but the effort is worth it and the effort is less than you'll have to make for any other finish like paint or glued laminate. Typical application is to apply a first coat diluted with white spirit (for penetration), leave it ten minutes, wipe off any excess with a rag** and leave it for 24 hours to dry. Apply a second coat of neat tung oil, ten minutes, wipe off, 24 hours drying. Repeat for a third coat, perhaps even a fourth for extra durability.

It has the same advantage as Danish oil, or any drying oil finish, in that application requires no skill to produce a good finish, and it can be revived by a light sanding and reapplication of one or two coats of oil. The latter isn't to be sniffed at as workbenches lead a hard life and it is nice to have an easy way to bring them back to pristine condition.

*'Drying' in this context actually means polymerisation in the presence of oxygen, not the evaporation of solvents.

**Beware of any drying oils and rags. As the oil 'drys' it heats up and trapped in a rag can catch fire - it's a recognised hazard in the fine furniture and decorating trades. I soak any contaminated rags in water, put them into a sealed polythene bag so they stay sopping wet and only then throw them away. Alternatively put them somewhere where it doesn't matter if they spontaneously combust like a metal tray on some hardstanding outdoors.

[Cerebus]

I prefer a thin sheet of hardboard (AKA HDF, Masonite, etc.) on the top of my workbenches.

Define "thin" - 1/4"?

Typical hardboard is around 4mm or 3/16".

[CharlieEcho]

Tung oil is good stuff. I guess you could even use good old fashioned shellac.

[Cerebus]

Tung oil is good stuff. I guess you could even use good old fashioned shellac.

Shellac is a pain as anything other than a sealing coat - thus speaks a man who once French polished a guitar: "Never again". As a sealing coat it can work wonders, especially with naturally oily woods like Cocobolo.

[CharlieEcho]

Shellac does get pretty laborious if you want to apply a few coats! Looks and feels nice, though. And can be refinished.

[CatalinaWOW]

If the benches are in a typical indoor environment where there is no weather exposure.  I would seriously consider no finish.  I have several benches used for a variety of work (machine, woodwork and electronics) that have been left unfinished for decades.  While they have developed some interesting stains from various spills over the years they are functionally the same as when they were built.  Most of the oiled, shellaced, varnished and other finishes mentioned in this thread will give the benchtop a very smooth, shiny surface.  While the smoothness is an advantage in some situations, the slight roughness of a sanded plywood surface has its own advantages.  The lack of shine is almost always an advantage.

There are two other advantages to this approach.  The first is that it is obviously a lot less work.  The second is that you don't regret the inevitable dings and nicks that will occur over time. 

The biggest disadvantage is that it really works best with plywood that has an A grade top surface, which costs very noticeably more than a construction grade sheet which could be filled and sanded to a good finish.

[Ian.M]

If the plywood has an A grade top surface, go with a drying oil finish to seal it but dont try to build up any significant film thickness.   If its got defects, then use exterior filler then floor paint.   In both cases, if you aren't going for a full bench ESD mat, protect the main work area with a sacrificial surface of hardboard, smooth side up so you don't have to worry about burns, scores and dents.

Formica or any similar laminates look good initially, but soon degrade under heavy use.  Excess heat in a spot can pop up a blister, as can many solvents, and they scratch and chip too easily.  Once the surface finish has degraded, and then been contaminated by flux residue which causes solder dross and other particulates to adhere, they are very difficult to clean.

[timelessbeing]

Plywood is durable stuff. It's used for exterior construction sheathing. You don't need to apply anything unless you have a specific reason to do so. Occasional spills won't harm it. It will last a very long time.

MDF is not nearly as durable as plywood. It's heavier, swells when soaked, and not a strong (brittle). MDF is good when you need a smooth finished surface, but since you're covering your surface with a mat, I wouldn't bother. It's also more expensive.