Satin vs gloss finish

[charles Tauber]

Originally Posted by Methos1979

Details, please.

I've written about his numerous times over the years and won't get into a long-winded repeat here.

The short answer is that the level of "gloss" is a function of how irregular is a surface. Smoother surfaces reflect light in a "spectral" way appearing more shiny. More irregular surfaces scatter light making the surface appear duller, less shiny. The difference between the two is how free of irregularities a surface is. Surface irregularities can be caused by a number of things including, dirt on a surface, scratches, "texture" of an applied finish, pores in wood and particles suspended in an applied finish.

Dirt can be removed with solvents or fine abrasives. One popular solvent that works well on dirt and grease is naphtha (lighter fluid). Dirt can also be removed using a "polish" - most polishes are a combination of waxes and fine abrasives. The fine abrasives removes dirt while the wax leaves a film that fills small irregularities, smoothing the surface somewhat, making the surface appear more shiny.

Abrasives, be they in polishing compounds, or on a backing, such as "sandpaper", come in a very wide range of abrasives from very, very fine to very course. Courser abrasive sheets are often used to level a finish during stages of initial finishing. Doing so removes highs and lows in the surface, evening out the surface - removing ripples, texture left by the finish applicator (spray gun, brush strokes...). While the abrasive levels the finish, it also leaves scratches that impart a dull shine to the finish. Scratches left by abrasives are removed by using a series of progressively finer abrasives with each finer abrasive removing the scratches of the previous abrasive. This is done until a desired level of sheen is reached.

At any point in the process, one can stop to accept the current level of sheen. For example, if one stops sanding with, say, 1000 grit "sandpaper", one will have a dull satin finish. If one continues through successive grits to, say, 12000, one will achieve a mirror finish. (Rubbing compounds are often used instead of or in conjunction with abrasive "papers" or sheets.)

Thus, if an area of a finish is too shiny - due to, for example, repeated rubbing against a shirt sleeve - one can increase the surface irregularities to make that area less shiny, matching a surrounding satin finish. One need only use the right level of abrasive to match the irregularities of the glossy area to that of the satin area. That might well be 1000 grit sandpaper. The amount of actual sanding needed is very small, often not more than a few strokes over the surface.

If an area becomes dull, and cleaning the surface with naphtha or a fine polish doesn't restore the finish to the surrounding level of gloss, one need only polish the area with one or more progressive grits of abrasive sheet or rubbing compound matching the level of surface imperfection to the surrounding level of gloss. This will typically take a bit more rubbing to remove surface imperfections than it takes to add them, in the case of dulling a too shiny surface. For example, for an area that has become dull, one might start with a typical red rubbing compound, rubbing a small amount on the surface with a paper towel. One then progresses to a grey or white rubbing compound, again rubbing a small amount on the surface with a paper towel. That can be followed by one or more final compounds, such as swirl remover or "polish".

Fine abrasive sheets, such as sold by Micromesh, and a few rubbing compounds are relatively inexpensive and will last for a very long time.

Note that some finishes can deteriorate over time and/or due to chemical attack. Those are special cases different than what is described above.

[Methos1979]

Originally Posted by Stevien

I believe Methos is referring to the top of the lower bout, where your arm hangs over. For many, this area gets cloudy & dull.
Steve

Yes, this is what I meant. And what I said.

[Methos1979]

Originally Posted by charles Tauber

I've written about his numerous times over the years and won't get into a long-winded repeat here.

The short answer is that the level of "gloss" is a function of how irregular is a surface. Smoother surfaces reflect light in a "spectral" way appearing more shiny. More irregular surfaces scatter light making the surface appear duller, less shiny. The difference between the two is how free of irregularities a surface is. Surface irregularities can be caused by a number of things including, dirt on a surface, scratches, "texture" of an applied finish, pores in wood and particles suspended in an applied finish.

Dirt can be removed with solvents or fine abrasives. One popular solvent that works well on dirt and grease is naphtha (lighter fluid). Dirt can also be removed using a "polish" - most polishes are a combination of waxes and fine abrasives. The fine abrasives removes dirt while the wax leaves a film that fills small irregularities, smoothing the surface somewhat, making the surface appear more shiny.

Abrasives, be they in polishing compounds, or on a backing, such as "sandpaper", come in a very wide range of abrasives from very, very fine to very course. Courser abrasive sheets are often used to level a finish during stages of initial finishing. Doing so removes highs and lows in the surface, evening out the surface - removing ripples, texture left by the finish applicator (spray gun, brush strokes...). While the abrasive levels the finish, it also leaves scratches that impart a dull shine to the finish. Scratches left by abrasives are removed by using a series of progressively finer abrasives with each finer abrasive removing the scratches of the previous abrasive. This is done until a desired level of sheen is reached.

At any point in the process, one can stop to accept the current level of sheen. For example, if one stops sanding with, say, 1000 grit "sandpaper", one will have a dull satin finish. If one continues through successive grits to, say, 12000, one will achieve a mirror finish. (Rubbing compounds are often used instead of or in conjunction with abrasive "papers" or sheets.)

Thus, if an area of a finish is too shiny - due to, for example, repeated rubbing against a shirt sleeve - one can increase the surface irregularities to make that area less shiny, matching a surrounding satin finish. One need only use the right level of abrasive to match the irregularities of the glossy area to that of the satin area. That might well be 1000 grit sandpaper. The amount of actual sanding needed is very small, often not more than a few strokes over the surface.

If an area becomes dull, and cleaning the surface with naphtha or a fine polish doesn't restore the finish to the surrounding level of gloss, one need only polish the area with one or more progressive grits of abrasive sheet or rubbing compound matching the level of surface imperfection to the surrounding level of gloss. This will typically take a bit more rubbing to remove surface imperfections than it takes to add them, in the case of dulling a too shiny surface. For example, for an area that has become dull, one might start with a typical red rubbing compound, rubbing a small amount on the surface with a paper towel. One then progresses to a grey or white rubbing compound, again rubbing a small amount on the surface with a paper towel. That can be followed by one or more final compounds, such as swirl remover or "polish".

Fine abrasive sheets, such as sold by Micromesh, and a few rubbing compounds are relatively inexpensive and will last for a very long time.

Note that some finishes can deteriorate over time and/or due to chemical attack. Those are special cases different than what is described above.

Lol - great response and information! Charles is my kind of guy. Says he won't get long-winded then writes a book!! Anyone that has read any of my NGD reviews knows that's exactly what I do - try to keep it short but then write a lot of detail. Oh well, what can I say, I like detail! More is better.

I've tried the napatha - did nothing for my finish for the forearm cloudiness. I should note that the gloss finish is still there and quite shiny but in the right light there is just this cloudiness to the finish. I guess I just have one of those body chemistries that reacts with guitar finishes be it satin or gloss.

Another thing to note, though I stated the both finishes suck for this feature, it's not something that bothers me. And it definitely doesn't bother me enough to take sandpaper or any abrasive to the guitar. It's the price of doing business. I buy guitars to play and I don't worry much about the areas of contact. Or dings. Or anything like that. I do try to take of them and don't deliberately bang them around and I do wipe them down but for me they are tools to be used and they will show signs of that use eventually.

The funny thing about those areas of contact is that for some reason the shiny spots on the satin guitars bugs me a whole lot less then the cloudy spots on gloss guitars. Probably because satin guitars just look less 'polished' to begin with?

[davidd]

You can buff out a satin finish to a nice gloss but not the other way around IMO. Abrasives will never look like a sprayed satin finish.

[Methos1979]

Originally Posted by davidd

You can buff out a satin finish to a nice gloss but not the other way around IMO. Abrasives will never look like a sprayed satin finish.

I've seen a few people here on AGF do that to guitars like the Martin 15 or 17 all-hog guitars and I generally like the finished product. It's not an over-the-top gloss-like finish but just a nice shine. Like the best of both worlds. Way too much work for my lazy self but for those that have undertaken it, I think the result is really nice.

[charles Tauber]

Originally Posted by Methos1979

Says he won't get long-winded then writes a book!!

That was the short version.

And it definitely doesn't bother me enough to take sandpaper or any abrasive to the guitar. It's the price of doing business.

Perhaps you've stated it correctly: it can be done, but many players aren't - and maybe shouldn't - be willing to do it.

[Methos1979]

Originally Posted by charles Tauber

That was the short version.

HA - love it! Yes, that would be about a medium amount of detail for my NGD reviews. I've started with just doing a 'Short version' summary at the top and then the much longer, more detailed version following immediately thereafter. And then the video review at the bottom. Something for all types!

[davidd]

Originally Posted by Methos1979

I've seen a few people here on AGF do that to guitars like the Martin 15 or 17 all-hog guitars and I generally like the finished product. It's not an over-the-top gloss-like finish but just a nice shine. Like the best of both worlds. Way too much work for my lazy self but for those that have undertaken it, I think the result is really nice.

It isn't too time consuming. I did this buffing of my Epi EF500RA in about 2 hours many years ago. The satin finish killed the beautiful rosewood figure.

[dwasifar]

Originally Posted by Peepaw

Neck has to be satin on the neck.

Yeah, I hate it when the neck is not on the neck.

[foxo]

Originally Posted by davidd

It isn't too time consuming. I did this buffing of my Epi EF500RA in about 2 hours many years ago. The satin finish killed the beautiful rosewood figure.

Have to say you did a great job, looks wonderful.

[Peepaw]

Originally Posted by dwasifar

Yeah, I hate it when the neck is not on the neck.

LOL, I saw how I stated that the other day and started to edit it. I left it be.
I may have been a little tipsy when I posted.

[Methos1979]

Originally Posted by davidd

It isn't too time consuming. I did this buffing of my Epi EF500RA in about 2 hours many years ago. The satin finish killed the beautiful rosewood figure.

Hard to really appreciate from that one shot but from what little we can see, it looks like you did an incredible job!