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  #1  
Old 08-12-2017, 12:47 PM
funkymonk#9 funkymonk#9 is offline
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Default Anyone use any coating thickness guages for Instrument Finishes?

I'm sure many builders have a finish procedure written in stone with wet mils and # of coats before final sanding to desired thickness.

But i was curious in that evolution if anyone used or desired a coating thickness gauge for a more precise measurement.

For new builds top thickness of the soundboard could be calculated first for later finish measurements, but if you are the type to want a precision thickness soundboard then maybe you are the type to want a precision finish as well.
Just curious.
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  #2  
Old 08-15-2017, 05:18 PM
Ned Milburn Ned Milburn is offline
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Best coating (no matter what medium) is only as thick as it needs to be. It is cumbersome and unnecessary to measure finish thickness. I have measured finish thickness of finish that has come from underneath the bridge (during bridge removal/reglue), just to know how thick some of the factories actually apply it. Other than that... no need.
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  #3  
Old 08-17-2017, 06:41 AM
Quickstep192 Quickstep192 is offline
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Do you mean this kind of gauge - the kind you drag through the finish while it's wet?

http://www.geionline.com/wet-film-gauge

I know auto paint guys swear by them. It would be a scientific approach to predicting how thick your finish coat(s) would be.
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Old 08-19-2017, 06:03 PM
funkymonk#9 funkymonk#9 is offline
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Quote:
Originally Posted by Ned Milburn View Post
Best coating (no matter what medium) is only as thick as it needs to be. It is cumbersome and unnecessary to measure finish thickness. I have measured finish thickness of finish that has come from underneath the bridge (during bridge removal/reglue), just to know how thick some of the factories actually apply it. Other than that... no need.
I understand your sentiment, it might be for purely curiosity, from which though you might develop some theories that might lead to methods. Obviously methods may have already been developed.

I don't understand how it is cumbersome to measure with the tool I referenced. It is used just like other thickness gauge except it is focused to work with coatings.
You said you were curious to know what factories used, so wouldn't it be useful even when you didn't have to take the bridge off to find out?

I suppose I am certainly guilty of taking things to far and applying a method to create "a finish only as thick as it needs to be" consistently on the instrument would seem useful to me.

Here is actually what i speak of: Not Cheap!
http://www.defelsko.com/applications/LacquerGuitars.htm
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Old 08-20-2017, 05:56 AM
Quickstep192 Quickstep192 is offline
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That's a cool tool! As a rookie finisher, it would be cool to know how much finish I need to build up so that I could sand and polish without the risk of sanding through. Through experimentation, finishing could become very scientific. With some testing it seems like it could be possible to build a finish to the bare minimum thickness to be able to sand and polish without sanding through.
But, as a rookie, I don't think I could justify dropping $1,000 on that tool and I suspect pros don't need it.
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Old 08-20-2017, 07:09 AM
mirwa mirwa is offline
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I don't measure my paint thickness, if it is info you are after on how to measure, then I can help on that front, can make one for around 50 bucks using new parts, cheaper if you want to chase down second hand bits.

In my aviation mechanic / inspector day's, I use to have to measure the thickness of the primer and topcoat layers after an aircraft was resprayed, the thickness correlates to a weight, all weights are counted in aviation, picture how upset a painter is when you tell them there is too much paint on the aircraft (yes I had to do that a few times).

Steve
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Last edited by mirwa; 08-20-2017 at 07:41 AM.
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  #7  
Old 08-20-2017, 12:08 PM
funkymonk#9 funkymonk#9 is offline
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Quote:
Originally Posted by Quickstep192 View Post
That's a cool tool! As a rookie finisher, it would be cool to know how much finish I need to build up so that I could sand and polish without the risk of sanding through. Through experimentation, finishing could become very scientific. With some testing it seems like it could be possible to build a finish to the bare minimum thickness to be able to sand and polish without sanding through.
But, as a rookie, I don't think I could justify dropping $1,000 on that tool and I suspect pros don't need it.
I agree completely, for pros who have a method and find it completely satisfactory, it is unnecessary. For amateurs who are looking for a tool that will assist in their method until they have gleaned enough research to do without, it is quite a price tag.

There is also the scientific angle, being able to distinguish finish and record thicknesses across all instruments in order to draw conclusions about its effects on the effectiveness of the instrument. Of course there is already much research and conclusions about the ideal finish.

Quote:
Originally Posted by mirwa View Post
I don't measure my paint thickness, if it is info you are after on how to measure, then I can help on that front, can make one for around 50 bucks using new parts, cheaper if you want to chase down second hand bits.
Yes I am curious how thickness could be measured by weight if it corresponds to guitar finishing as well.
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  #8  
Old 08-20-2017, 05:21 PM
mirwa mirwa is offline
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Apologies for confusions, it's not measured by weight.

In aviation weight is critical, imagine how much paint goes on to an aircraft when being resprayed.

When we measure the thickness of the paint at locations around the aircraft, that thickness calculated into the surface area of the aircraft can give us a paint weight.

If it is still of interest, I can do a small tutorial this week showing how to use cheap parts to calculate paint thickness

Steve
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Last edited by mirwa; 08-22-2017 at 07:35 AM.
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  #9  
Old 08-22-2017, 09:09 PM
Larkins Larkins is offline
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I would be interested in this
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  #10  
Old 08-23-2017, 06:16 PM
mirwa mirwa is offline
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Did not work, I was using a magnetic field and a field indicator, it works a treat for detecting a total thickness (less than 5mm)

It was impossible to differentiate the paint layer and wood layer, this means if your top is not uniformily thick to start with, then you cannot accuratley say the paint is this thickness at this location and the wood is this thickness.

Bummer, will keep thinking on it.

Steve

Field indicator bottom right

Thickness measuring
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Last edited by mirwa; 08-23-2017 at 06:23 PM.
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  #11  
Old 08-24-2017, 07:41 PM
Quickstep192 Quickstep192 is offline
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Would it be possible to use your device to measure the wood thickness "before" the finish was applied and then measure again after finish was applied and calculate the difference?
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  #12  
Old 08-24-2017, 09:43 PM
JonWint JonWint is offline
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The MAG-ic Probe has the following specs:

Resolution 1 mil (decreasing after 10mm)
Accuracy 3 mil - 0.1mm

In use, I seem to be able to repeat measurements to 1 mil. So the relative change in thickness may be more accurately measured than the absolute thickness. I'll experiment with some French polish when I get a chance.

I'll use some small samples of wood that will allow me to measure with the probe, calipers, and micrometer.

Sample of MAG-ic Probe measurements/contours:

[IMG][/IMG]

[IMG][/IMG]

Last edited by JonWint; 08-24-2017 at 09:55 PM. Reason: photo added
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  #13  
Old 08-24-2017, 09:59 PM
mirwa mirwa is offline
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Quote:
Originally Posted by Quickstep192 View Post
Would it be possible to use your device to measure the wood thickness "before" the finish was applied and then measure again after finish was applied and calculate the difference?
Absolutley, but as per jons post, you need to map the whole thing out first, which is really too much work IMO.

I had not given any thought to the small variations across a top when being made, just a theoretical its 2.6mm example, however in reality when I used the system I found lots of variations, well on my builds I did .

Steve
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