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Top joint separation, satin finish
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=51647		 Page 1 of 1
Author:  Pmaj7 [ Mon Feb 25, 2019 5:12 am ]
Post subject:  Top joint separation, satin finish
Is there any way to fix a satin finish and have it blend in?

New username, same Pat Mac
Author:  Hesh [ Mon Feb 25, 2019 5:50 am ]
Post subject:  Re: Top joint separation, satin finish
Hey Pat :)

Sure depending on the finish. I don't do finish repairs but Dave does some, mostly smaller stuff and we like satin finishes specifically because blending in a finish repair is often easier than with gloss nitro.

Again this is not my bag and we don't spray much at our facility because the authorities at the People's Republic of Ann Arbor have asked us to limit our spraying of toxic chemicals so as to not ruin the enjoyment of someone eating a falafel or taco when fine dining next door..... Please note sarcasm....

I do know that Dave likes those white 3m abrasive pads to rub satin finishes out a bit and blend in what he's sprayed on them.

Anyway but yes satin finishes are certainly repairable but what was originally used will have bearing on to what degree, ease, etc. Can't offer much more sorry but I could answer your basic question so in the words of Mick Jagger "so I did..." :).
Author:  B. Howard [ Mon Feb 25, 2019 8:06 am ]
Post subject:  Re: Top joint separation, satin finish
While as I do lot's of finish work and will not attempt to blend satin finish on a repair...
Author:  Woodie G [ Mon Feb 25, 2019 9:24 am ]
Post subject:  Re: Top joint separation, satin finish
For satin lacquer, which is usually quite thin in terms of coating thickness, we repair the crack, drop fill, scrape level, and airbrush satin lacquer onto the seam. Further adjustment can be made with Micromesh or similar abrasives, but what I believe gives the best outcome - and the most expensive repair - is to remove the pickguard, prep the top with non-woven abrasive (aka ScotchBrite), mask body edge, fretboard extension, and bridge, and spray 1-2 well-thinned coats of instrument lacquer with gloss adjusted using flattening paste...with obvious concerns re: getting the mix right.

An alternative is to use a canned satin with added canned gloss to approximate the level of gloss of the existing finish. Lacquer work can be complicated by the 'Velveteen Rabbit' effect seen on older satin lacquer-finished instruments. And worth noting that we have had a few customers that used the repair opportunity to have the top converted to a gloss top, although this will usually give a silky semi-gloss at best unless the top is reshot with 3-4 coats of thinned gloss.

For CA repairs of polyurethane or polyester finishes, overspray is usually not a viable strategy unless you spray the original finish yourself, so mastering the use of abrasives such as ScotchBrite and Micromesh is the most viable strategy. What little skill I have developed in this regard has been aided by repairing old, condemned bodies and spot refinishes on the buffing 'mules' the students use to gain insight before committing their own projects to the wheel.
Author:  B. Howard [ Mon Feb 25, 2019 12:38 pm ]
Post subject:  Re: Top joint separation, satin finish
Woodie G wrote:
....., but what I believe gives the best outcome - and the most expensive repair - is to remove the pickguard, prep the top with non-woven abrasive (aka ScotchBrite), mask body edge, fretboard extension, and bridge, and spray 1-2 well-thinned coats of instrument lacquer with gloss adjusted using flattening paste...with obvious concerns re: getting the mix right.
.


The only satin repairs I do are done this way. Refinish an entire panel.

You also mentioned the thinness of the satin finishes and this is the problem with abrading a satin finish to blend the repairs (steel wool, scotchbrite, etc...) which is sand through. Typical factory satin finishes have just one coat of satin over a completely level sanded gloss coat as overall durability of the finish is better with this film stack than with just satin clear alone at the same thickness. This is the reason most satins get glossy with wear.... not the polishing of the surface but the wearing away of the softer satin slowly revealing the gloss underneath.

Understanding how things were done the first time around is key to making good repairs with minimal effort.
Author:  Clay S. [ Mon Feb 25, 2019 5:31 pm ]
Post subject:  Re: Top joint separation, satin finish
For furniture touch up we would go with a lower sheen (Mohawk offers different sheens in spray can lacquers - dead flat being the lowest) than what we were touching up. Cleaning the finish and giving the entire top a light misting can help blend the repair.
Author:  Mike OMelia [ Mon Feb 25, 2019 5:44 pm ]
Post subject:  Re: Top joint separation, satin finish
Isn't satin a lot like Eggshell paint? Better if u do the whole thing (top, or bottom, or side?) I would (and do) think a gloss is way easier to repair. Especially if we are talking nitro
Author:  Freeman [ Mon Feb 25, 2019 10:00 pm ]
Post subject:  Re: Top joint separation, satin finish
I make no promises about how the finish will look when I do any repair, but I have had some luck with cracks in satin finished guitars where I try to stabilize them with CA, scrape the repair and then lightly scuff with steel wool.
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