Any shortcuts for spar varnish?

[Woody Knotsensplintahs]

Hi,
We almost always use oil-based polyurethane spar varnish in our DIY projects.

Previously, with free-standing cabinets, we have gone the whole route of 6 coats of hand-applied varnish with sanding, etc., and then a full round of hand polishing with compounds before waxing.

Our current project is a set of wall cabinets, and we are hoping to shortcut the finishing process as there is a lot of surface area, and the cabinets are for utility in a pantry/storage room.

Another challenge we have is the pervasive presence of dust. We are varnishing in a spare bedroom temporarily converted to the paint room because the workshop is not heated. The house is clean, and we clean the wood by brushing, vacuuming, hand dusting, etc., but the glossy finish still has specks of dust. We live in the southwest desert; the dust is in the air.

Each time we sand, the dust smooths right over.

For the shelves, we are at three coats with a fairly even glossy finish that we would normally level with 600 grit. But, I hesitate because I suspect when we are done, we will feel obligated to add yet another coat due to the minor unevenness revealed by the sanding process.

For the doors, we intend to go through the full process.

I am writing to ask if anyone has suggestions for processing the shelves. Is it possible to get an even appearance with a final finish when the coating has not been adequately flattened?

Can we fake it by jumping ahead to hand polishing?

A nice, even finish is all we want. We are not necessarily hoping for a high gloss.

Thank you.

 

[Packard]

I’m not even sure spar varnish is the best oil-based poly to use on cabinets.

Spar, and all exterior grade poly, are designed to be flexible to withstand the temperature changes and the associated wood movement.

Interior grade oil-based poly, as a rule, is a much harder, more abrasion resistant finish. 

I don’t brush it on; I wipe it on.  And I won’t spray it either.

I have sprayed water based poly, and if you are looking for a compromise that is faster and easier to use, that is what I would do. 

I tend to over-brush, so I don’t do well brushing water based poly.  But if you can refrain from over-brushing, the water clean up and no odor, and the quick dry, and quicker time to recoat, then the water based poly is the interior short cut I would take. 

Even then, I like to lay down an coat of SealCoat de-waxed shellac.  It prevents raising the grain, and is an excellent “primer” for all clear coats.  It also dries in about 20 minutes and seals the wood, so a second coat can be applied sooner and it seals the wood so that coating thickness builds faster.

An aside is that shellac is an effective odor sealer. If you are refinishing a cabinet where the previous owner was a smoker (or he let his cat pee on his cabinets) this will seal in the odor.

Likewise B-I-N primer is shellac based and pigmented (white).  It can seal odors on painted walls and act as an excellent primer.  It does have a heavy odor that dissipates in an hour or two, so best applied when it is feasible to have the windows open.

 

[Woody Knotsensplintahs]

FWIW, I am asking about spar varnish.

I should have elaborated by explaining that we use Foam "brushes" to wipe the varnish on rather than traditional bristle brushes.

Some of our DIY furniture finished with spar varnish is now several decades old, still looks exceptional, and almost always catches the eye of a first-time visitor who recognizes the furniture as handmade and marvels at the lustrous and smooth finish.

What I especially like about spar varnish is the option to refinish with minimal fuss, but we have yet to need to.

Hoping some one with spar varnish experience can offer some suggestions.

 

[smorgasbord]

Well, first of all, we're going to have to know which specific spar varnish you're using. The term "spar varnish" doesn't specify the chemisty involved at all, but merely designates, at least in the US, that the finish is suitable for outdoor use. Different companies will use different oils, different resins, and/or different solvents in the spar varnishes, and what's used will affect whether you can sand through layers without layer marks showing.

Here's a brief explanation:https://thewoodwhisperer.com/articles/difference-between-spar-varnish-and-regular-varnish

and he also has an article on applying it:https://thewoodwhisperer.com/articles/a-better-way-to-apply-spar-urethane/

 

[Woody Knotsensplintahs]

In the past, we lived on the coast and used Modified Alkyd Resin McCloskey Man O War satin Marine Spar Varnish because it seemed like good stuff and was easy to find at our local paint store.

I know the McCloskey isn't as prestigious as Phenolic Epiphanes. We use the finish for our interior woodwork and DIY furniture rather than brightwork on the deck of a million-dollar yacht, so we felt ok about making a budgetary compromise.

Now, we live deep in the heart of the southwestern desert, in a small town, 120 miles from the next small town, where a few years ago, I found a can of Polyurethane Rust-Oleum Marine Coatings Spar Varnish on the shelf at the hardware and sundries store and decided to give it a try.

Having previously thought one needed to purchase and use a decent boatbuilder brand of spar varnish, I was more than a little surprised at how pleased I have been working with the Rust-Oleum product, so I have continued asking for it and using it on my projects.

Thank you.

 

[Packard]

There is a perception that because Minwax/Rustoleum products are so widely available that they must be “homeowners’ grade”. 

In magazine comparison tests their products are usually rated #2 or #3 out of ten products; and never near the bottom.

They are huge company with a huge research staff and budget.  Yes, they are watching their bottom line (and so are the little guys), but in general I have found that their products are uniformly very good to excellent. 

And as far as prices go, Rustoleum/Minwax’s pricing is not bargain basement.  The bigger savings are to be had by shopping around.

I always comparison price Amazon/Walmart vs. Big Box stores for these products.  For SealCoat recently, Walmart was the clear (pun) winner on pricing and delivery.  Returns are a breeze; I just drop things off at the nearest Walmart store. 

Note:  Walmart, like Amazon, has a lot of 3rd party sellers.  Some are competitive, but some are out to make a big buck.  Watch the price and the shipping charges.  Some of the sneaky vendors have $20.00 or $30.00 or nearly $40.00 shipping charges.  So watch that.

 

[smorgasbord]

Any slow drying finish is going to get whatever's floating in the air stuck to it. You need a clean room, and probably with a recirculating HEPA air filter.

As for the sanding, a couple points:
1) Are you brushing the finish or spraying? Spraying can be applied more thinly, so may dry faster, reducing the things getting stuck in the finish. Your finish is available in spray cans.
2) You need to test to see if sanding through one coat into the previous coat leaves a ring. You may only see that when you polish the sanded areas.
3) Going to 600 grit isn't fine enough for polyurethane since you apparently like a glossy finish. You probably need to take that up to 3000 at least, maybe 5000, and then finish with some polish. Look for Sedge videos on using the RO90 for polishing.
4) Read the page on your finish (https://www.valspar.com/en/mccloskey ) and you'll see that it's advertised for outdoor needs. Those are usually less critical in terms of small flaws than indoor finishes.

 

[podz]

I keep the dust from settling in my paint room while the lacquer is drying by running a rotating fan on low speed.

The fan is a wall-mount model, but I just used a pair of 6" Bessey squeeze clamps and fixed it to my tall Makita light tripod pole thingy.

The low speed is the key - it will speed the drying somewhat, but you still don't want the lacquer drying too fast.

 

[Woody Knotsensplintahs]

Are you suggesting the fan keeps the dust aloft and prevents it from settling?

It seems counterintuitive to blow dust around the room, but it also seems like a brilliant insight to consider that dust floating in the air might never have a chance to land on a surface.

I wonder how the significantly different dry times between laquear and varnish would affect the results.

Thank you.

 

[Packard]

I have seen people use exhaust fans in spray painting areas. 

That is wrong.

It sucks dust into the room.

Better (much better) is to blow filtered air into the room.  Something as simple as using bungee cords to attach a 20” x 20” furnace fan to a box fan.  Not only does this blow fresh air into the room for better breathing, it also reduces the amount of dust into the room.

“Positive atmospheric pressure” is the basis of clean room technology. Easy to do and smart too.

 

[podz]

Are you suggesting the fan keeps the dust aloft and prevents it from settling?

It seems counterintuitive to blow dust around the room, but it also seems like a brilliant insight to consider that dust floating in the air might never have a chance to land on a surface.

I wonder how the significantly different dry times between laquear and varnish would affect the results.

Thank you.

Works for me. YMMV.

No need to ruminate, just make a little test yourself and find out!

 

[Mini Me]

Exhaust fans can work if the air entry is filtered. I built a sanding room using a Clearvue cyclone for extraction for a commercial chair maker and all the sanding was done in that in the same fashion as a spray booth for cars. It had a secondary advantage of keeping the production area as free as possible from the micro dust created by sanding which the staff thought was a great idea. There are a lot of temporary spray booths on YT some using plastic sheet or even cardboard boxes.

 

[leakyroof]

Are you suggesting the fan keeps the dust aloft and prevents it from settling?

It seems counterintuitive to blow dust around the room, but it also seems like a brilliant insight to consider that dust floating in the air might never have a chance to land on a surface.

I wonder how the significantly different dry times between laquear and varnish would affect the results.

Thank you.

  As noted, there are fast drying varnishes, and slower ones. Regarding Epifanes, they DO make a fairly fast drying varnish, Rapid Clear.  It will dry much faster than their traditional Gloss Varnishes. But, as noted, this is something you'd be ordering in versus in stock on a shelf for the most part. It puts a thinner coat on in terms of Mil Thickness when brushing, but dries quickly so up to 3 coats can easily be done in one day , with no sanding required for coat adhesion, just dust nib removal if needed
Otherwise, except for room treatment of the air as in the posts above, I'd switch to a Water Based Spar Varnish. Don't know if they still make it, but Old Masters Water Based Spar Varnish was excellent for me.  If not them, then General Finishes or someone else. You'll get fast drying ,low odor, and the ability to put several coats on in one day, even if you had to lightly sand some dust nibs away between coats.

Update:::, apparently Old Masters has renamed their Water Based Exterior Varnish to : Ascend Exterior.  No idea if this is as good as the old Water Based Spar Varnish was. But, they're still touting it with UV additives, so maybe it was more of a name change than a product change... [huh]