Steaming over satin nitro finish...

Lacquer is an ideal candidate for steaming out shallow dents because it is porous and the steam will penetrate to swell the wood and raise the dent. Done carefully, without abrading the finish, you can do an invisible fix.

 

So you're going to "steam" out a dent in a nitro finished guitar, and nitro is a "ideal candidate" for steam... I'll look for your post on how to remove the blush.

 

Its inevitable that our guitars pick up dings and scratches along the way. Embrace them.

 

That shows what you know ... cured lacquer does not blush, wet sprayed lacquer blushes.

I’ve steamed out a couple dozen dents and lacquer is the easiest to do as the lacquer is a permeable coating.

 

Steam could absolutely cause a hazy finish. Just google search "haze martin neck reset".

There are many proposed cures for a hazy finish caused by steam, from waiting it out, to naptha, to virtuoso polish. One remedy even suggested doing a French Polish technique with acetone. I am sure both gloss and satin finishes each have their own unique problems with any of these remedies. I would absolutely test in an inconspicuous area first.

Or you could just leave the mojo and gather some more.

 

Cured lacquer is lacquer that is fully dried and in a solid state. Wet sprayed lacquer is still in it's liquid form.

Blushing is the result of spraying lacquer in high humidity conditions. As the lacquer dries, the solvents the lacquer is dissolved in evaporate (referred to as flashing) and the lacquer is deposited on the surface as a solid. When you have have evaporation, you have an evaporative cooling effect and the lacquer drops in temperature. If the temperature of the lacquer drops below the dewpoint (the temperature at which water vapor in the air condenses and becomes a liquid), the water vapor condenses on and in the lacquer and causing a cloudy finish ("blushing"). If drying is slow, the water evaporates as the lacquer "dries" and the lacquer's clarity is restored. If the lacquer dries (solvents flash off) faster than the water trapped in the lacquer, the blushing becomes trapped under the dried lacquer surface. When this occurs, it is common to spray the surface with a retarder or "blush eraser" before the lacquer fully dries which will "re-melt" the lacquer and slow the drying down to allow the blushing to evaporate.

If you look at lacquer under a microscope, it looks like a deposition of fractured crystals with gaps, fissures and voids between each other. This is what allows you to steam a shallow dent up without affecting the finish as long as you don't heat the lacquer to the point where it discolors. Moisture migrates in and out of lacquer. This is where most people get the idea that polishes are bad for lacquer and mistakenly read "contains silicone" where the label actually says "contains silicates". A silicate is a finely ground grain of silica (like sand) that polishes the lacquer by mechanical means and also deposits itself in the cracks and voids between the lacquer crystals. This makes the surface smoother and protects the finish from water and water vapor penetrating the finish and damaging it.

It is also the reason why guitars finished in lacquer feel different than those finished in polyurethane or polyester. Those finishes are a non-pervious film coating with no gaps. Steaming a dent out of a poly finished guitar is an exercise in futility. You can make a sacrificial cut through the finish or even make multiple pin point holes through the finish to allow the steam to penetrate. At that point, it is just easier to drop fill and level the dent with CA and not disturb the finish than steam it out and attempt to repair the damage you just inflicted.

 

The finish was overheated as a collateral damage in to order to melt the glue. The finish softened and absorbed moisture. Any time you add concentrated heat to a finish, you run the risk of overheating it and suffering the consequences.

You don't need the amount of heat required to melt glue to steam up a dent. I use a household steam iron and a damp, folded over wash cloth applying the iron for short periods, always checking the progress and allowing the finish to cool between applications.

The only thing that would worry me about the OP's situation is the matte lacquer which has a tendency to get shiny from handling

 

My Taylor 816ce was "mojoed" by its prior owner in the form of "pick scratches" that indent the woodgrain, but do not break the surface of the finish. The top is gloss finished. Would this be a candidate for the "steam iron and damp washcloth" method of dedinging?

 

Hard to say. If the finish is only indented down into the wood, yes you should be able to steam them up. If finish has been removed by the pick scratches it will still show as a scratch but the odds of wet sanding it out are better by reducing the overall depth of the scratch. Just be very careful not to overheat the lacquer.