Repair finish

[joe oski]

It's a store bought oak table, somewhat of a pecan color
I've no idea, what the current finish is, but someone spilled nail polish remover on it.
WHOOSH,
was wiped with paper towel and all the finish is gone ( no signs of color change). Would make a great stripper if I had time to refinish the whole top. Right now I only want to seal it/before it gets permenantly stained. Maybe blend it in.
In the future, given the abuse and grandkids around here, I was thinking poly.
In the meantime do you think I can just wipe a little poly on there and not cause me any future finishing problems, or would this be the time to figure out whats already on it.
I've no idea what chemical nail polish remover is, or how long it sat before being wiped/blooted? up. But there is a distinct edge to the remaining finish, like it was just peeled off.

[Ken Fitzgerald]

Finger nail polish remover used to be acetone. I have no idea what it is today.

[Jim Rimmer]

+1 what Ken said. It smells just like acetone and evaporates just about as fast.

[Scott Holmes]

Most polish remover is acetone albeit very WEAK compared to what you get in the can of ACETONE at the hardware store.

Poly would not be a good choice...adhesion problem etc. I would try covering all but the damaged aera with tape then lightly spray with lacquer or shellac. Shellac is less likely to damage the existing finish; lacquer may, but most likely will not hurt the factory finish.

You can then remove the tape and buff it to blend.

[joe oski]

"Poly would not be a good choice...adhesion problem etc."
Your kidding!, I thought it was finish of choice for wear surfaces like floors, I would have thought an abused table would have benefited. For an abused table you would recommend?

Will see about getting some shellac, for the repair.

Lacquer, is this the same stuff I used to put on cars with metalflake?

[Scott Holmes]

This is a table correct?

Poly has one excellent trait... extreme abrasion resistance aka walking on it with shoes. That's why IMHO (not really humble) POLY is for FLOORS.

IT has many less desirable traits...

1. does not stick well to itself or anything else.
2. Must be sanded between coats (cause it doesn't stick well)
3. Is very prone to UV damage
4. It's cloudy when compared to other varnishes
5. It is tough it is not that HARD
6. edges show up so you can't feather and blend in repairs.
7. Very cheap to make; so, big $$$ for the manufactures... hmmm... is that why it gets all the advertising?

There are more but I don't want to stand on this soap box any longer...

NC lacquer for wood finishing is a bit different than what you use on metal.

[joe oski]

but at the moment sounds like the factory probably used lacquer for its fast drying ability
will have to study more on finishing,
do you have a good thread or site recomendation

[Scott Holmes]

Most factory finishes are conversion varnish; not lacquer anymore. CV dries as fast and is more durable, meaning they can pack it and crate it sooner and safer.

[joe oski]

local hardware did not carry shellac, so I just wiped some poly on the table to seal it before the next staining spill occurs

Hmmm, my supply pile has some spar ur
that at least would have some uv resistance, although table is currently in a north window and sunbleaching is not a problem

[Scott Holmes]

Spar is softer and LESS waterproof than interior finishes. Not good on a table

[joe oski]

I knew spar to be softer, more flexible, to put up with the dimensional variance of wood outside. Would have thought its waterproofing to be at least as good if not better.
I'll just have to hang around the finishing area, and I'll have be thoroughly confused/informed by spring

[Neal Clayton]

it seems confusing at first but after a few years of messing with this stuff you realize it isn't, nothing much changes about the finishes, just the marketing of them gets confusing.

there are varnishes, there are lacquers, there are urethane based finishes, there are acrylic paints and there are oil paints.

resin varnishes tend to penetrate and after multiple coats build a slight film. they are very flexible and typically very waterproof. they are a combination of a natural drying oil (tung, linseed, etc.) with a solvent (naphtha and/or mineral spirits) and a resin of some sort. the resin leaves the film on top. these are probably the easiest finishes for a layman to apply, since they dry very slowly gravity will level and "fix" them by itself as they dry. all you have to do is apply it evenly and make sure it doesn't run or drip.

lacquers are surface film finishes that are designed to dry very fast. they are harder and more resistant to scratches and dents and such. that's why people finish furniture with them. they can be brushed, but will have to be buffed and polished after to get an even sheen. much easier to spray with good results.

shellac acts like lacquers in that previous layers blend with new layers. it's also very fast drying. shellac will also penetrate like a varnish onto raw wood and act as a good sealer. after many coats it can be used to build a film like a lacquer. as a barrier coat between finishes it can bind two incompatible finishes together, too. given practice/technique, it can be applied well with a brush and then buffed to a lacquer'ish sheen. otherwise easier to wipe/spray in thin coats.

polyurethane based finishes, such as floor varnishes, as scott mentioned are abrasion resistant and flexible but don't have many other desirable traits. they do not stick to themselves once cured, therefore are difficult to repair without a complete sand/recoat. they are softer than lacquers so the resulting film will scratch more easily from say...a knife or fork hitting a table. that's why they're not used for furniture all that much.

acrylic paint is typically talc/quartz dust pigment in a binder borne by water. it fails by the pigment gradually falling off as it gets chalky from the pigment losing hold of the binder.

oil paint is a metallic pigment (the pigment dust coated with silicone these days since you can't use lead anymore and other metals deteriorate too fast) borne in an oil. dries to a thick film. when the oil gradually all dries up, it fails by cracking and complete separation from the substrate. on the upside, until then, it is highly protective from the sun, highly water resistant, and highly protective of abrasion damage.

when talking about paint, "enamel" refers to a hard, durable paint film. anything other than "enamel" will be softer, and in the case of interior wall paint, sticky'er. so always use an "enamel" on things that you touch, or things that other things touch (lest you find your vases and pictures stuck to your shelves).

there you go, no matter what kind of paint or finish advertisement you see, if it's sold to the general public it'll be one of the above. if you read the MSDS for any product you can quickly determine what type of finish it is and dispense with the marketing BS and get right to the truth about it .

[Scott Holmes]

A few modifications or clarifications to Neal's comments...

Resin varnish are film forming finishes. Oil/varnish blends are not.

Polyurethane is a resin used to make varnish. It is not a class or type of finish, it is merely a varnish made from urethane resins.

Varnishes are not a simply... "they are very flexible and typically very waterproof. they are a combination of a natural drying oil (tung, linseed, etc.) with a solvent (naphtha and/or mineral spirits) and a resin of some sort. the resin leaves the film on top." as Neal stated.

A resin (Alkyd, phenolic or urethane) are combined with an oil (tung, linseed or soya (soybean)) and COOKED in the absense of oxygen, (no solvent is used). This process causes a chemical change in the oil and the resin and it forms a new molecule knonw as VARNISH.

This varnish is then thinned to a useable or now-a-days and almost usuable thickness and put in containers. When the thinner evaporates the surface is dry-to-the-touch. When the chemical reaction takes place between the VARNISH and the oxygen in the air the fiinish cures.

As for very flexible and very waterproof... Spar varnishes are very flexible because they are long-oil varnishes; interior varnishes are know as short-oil varnishes.

Any that is called interior and exterior is probalbly a long-oil varnish that the marketing guy said "HEY we can sell more of this if we say..." Of course it wont last as long on an interior table and that's going to cause more sales... HMMMMM.

The real claim to FAME for TUNG OIL is that VARNISHES made from tung oil are better at moisture and water protection than varnishes that are made from linseed or soya oil. Regardless of the resin used. The SOFTER the finish the less it will provide waterproofing and moisture proofing.

So poly is at the bottom of the list; I don't think there is a poly varnish made from tung oil and urethane resins are the toughist and the SOFTEST of the resin used to make varnish. Exterior (long-oil) makes it even softer...

Phenolic are the hardest, most UV resistant and add amber color as much as urethane.

Alkyd are the clearest, realitively hard and do not add much amber or yellow much with age.

Urethane is in between on color, tougher, softer, less optically clear, GHLY susceptable to UV damage, and has poor adhesion traits; it can't be used over many other products.

[Neal Clayton]

yea perhaps i oversimplified, i should've noted "interior" varnishes denoting short oil varnishes, scott's clarifications are correct. exterior varnishes don't really apply to this discussion of an inside table.

waterlox makes a polyurethane varnish, i'm not sure if it's tung oil based like their other varnishes though. if it is, it's the only one i know of.