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Finishing critique

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Finishing critique

Postby Steve Sawyer » Wed Jun 07, 2017 4:16 pm

Would appreciate getting some thoughts on my testing. The pic shows a sample tile finished with WB GF Enduro sanding sealer (pigmented white), then pigmented WB lacquer (GF High Performance), followed by the same product un-pigmented as a clear coat.

The pic shows some obvious scratches that I'm assuming were caused by either contamination of the finer grades of sandpaper, or could have been due to the fact that I found myself short of P600 wet-sanding paper, and had to jump from 320 to 800, but welcome any other suggestions.

I had about 8 coats of clear coat sprayed, using the schedule of 3 quick shoots (waiting about 20 minutes to let the previous shoot dry to the touch) for each coat. Each coat was allowed to dry overnight and then block-sanded with 320 before applying the next coat, and the resulting finish looked good - no fisheyes, sags, runs, or obvious orange peel, just a few dust nibs after each coat which the sanding addressed.

I then block-sanded with 320 dry, followed by wet-sanding with 800, 1200, 1500 then 3200 micro-mesh, then Meguiars 105, and Meguiars swirl-remover. Both polishing/buffing products were hand-applied.

Beyond the obvious scratches, the finish is less than ideal (look at the far right end of the fluorescent bulb reflection), and I'm not sure if the problem was moving too quickly through the grits, not block-sanding after moving beyond 320, the fact that I jumped from 320 to 800, or some other factor. I've never tried to achieve this kind of finish, so this is all new to me.

IMPORTANT NOTE: I sprayed this with a double-action airbrush using a small tent-style "spray booth" with an exhaust fan and filter. The overspray was not an issue with these sample tiles (about 2 1/4" x 7"), but when I tried to spray the body of the guitar with the sanding sealer, the overspray was drying fast enough that it passed completely through the filter and filled the shop with enough invisible paint dust that it set of the smoke detector (and yes, I was wearing a respirator). I decided that this was NOT going to work, and am waiting on delivery of rattle-can nitro primer, color and clear-coat from ReRanch. I will be taking advantage of the summer weather to do the finishing in the open garage if I can dodge the humid days.

Anyway, take a look and let me know what you think my mistakes were.

Thanks!

Finishing Test.JPG
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Re: Finishing critique

Postby Peter Wilcox » Wed Jun 07, 2017 6:08 pm

Does the orange peel follow the grain? What kind of wood?
My guess is that you flat sanded and polished too soon. I think after you apply all the coats, you need to wait 5-7 days before flat sanding. The finish probably shrinks for several days after application, and may have different rates depending on which part of the grain it overlays.
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Re: Finishing critique

Postby Aaron Helt » Wed Jun 07, 2017 8:20 pm

I think the scratches you see are probably from the 320 grit. Use 800 to level between coats and to level final, then go to buffer.
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Re: Finishing critique

Postby Steve Sawyer » Wed Jun 07, 2017 10:54 pm

Peter Wilcox wrote:Does the orange peel follow the grain? What kind of wood?
My guess is that you flat sanded and polished too soon. I think after you apply all the coats, you need to wait 5-7 days before flat sanding. The finish probably shrinks for several days after application, and may have different rates depending on which part of the grain it overlays.


If you zoom in on the far right of the pic, you'll see that the orange peel does slightly follow the grain. This is alder.

Re the 5-7 day wait - I've got several more tiles that I can experiment with, and let them cure for a full week before repeating this part of the process.
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Re: Finishing critique

Postby Steve Sawyer » Wed Jun 07, 2017 10:55 pm

Aaron Helt wrote:I think the scratches you see are probably from the 320 grit. Use 800 to level between coats and to level final, then go to buffer.


Wow - starting with 800 huh? Interesting. As I mentioned to Peter, I can use one of the other tiles to try that.
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Re: Finishing critique

Postby Mike Conner » Thu Jun 08, 2017 6:07 am

Steve,
My experience with Endurovar confirms that waiting 5 to 7 days for level sanding and buffing is needed to allow the finish to fully cure and shrink, and some of that finish shrinkage may be transport of the water absorbed into the wood surface.

I level and rough buff at 5 days, then finish buff at 10 days.

One way to monitor the curing progress is smell. EnduroVar has a distinct odor, sort of "sweet" and not the ammonia odor typical of most WB poly. I have a really good sense of smell and can sniff close to the curing surfaces. Most of the odor has faded by the 5th day.
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Re: Finishing critique

Postby Barry Daniels » Thu Jun 08, 2017 9:04 am

Hard to tell from your photo, but I think your equipment may have been part of the problem. It is hard to get an airbrush to lay enough finish down for a full wet coat. They are better for small touch ups or maybe a sunburst. Also, there is nothing wrong with using 320 grit sandpaper for leveling between coats. The next full coat should fill in the scratches easily. Since you are still seeing scratches, this is what leads me to say that you are not laying down thick enough coats. Orange peel is usually an indication of too much air, which also may be part of having insufficient finish in your mix.

Also, I think I have indicated to you before my opinion of spray cans. I don't think they are a solution to your problem. I suggest a real air compressor and spray gun. Those are the right tools for the job.
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Re: Finishing critique

Postby Gordon Bellerose » Thu Jun 08, 2017 10:17 am

I have to agree with Barry.
In my early attempts at finishing, I went through a few different stages before finally being able to lay down a good finish.
One of those was having too small a gun, and too small a compressor.

I realize that for someone who may only want to build one or two guitars, that this is a significant expense. For a professional result sometimes you need to spend some money.
I need your help. I can't possibly make all the mistakes myself!
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Re: Finishing critique

Postby Steve Sawyer » Thu Jun 08, 2017 4:40 pm

Barry/Gordon - I smell what you're cooking. I have more money than I'll admit to the wife invested in my shop, so I would be happy to invest in better spray equipment, the problem is space to do the spraying. While I could rig up a collapsible spray booth, basement shops (especially in basements with glass-block windows) are tough to exhaust, and it seems that you really have to have that to do this properly/safely.

This won't be my last guitar, but will probably be my only guitar with a pigmented finish. My first electric guitar was a Tele, and I've lusted for another one ever since that one got stolen, and (foolishly perhaps) set my heart on a seafoam-green version (and yeah, my mix was just a tad off on those test tiles). My experience with furniture making has made me comfortable with wipe-on oil finishes, and I've seen some really gorgeous guitars finished in that way, so I'm expecting to follow that path after I get this one completed, which will be another learning curve I'm sure! :D

Bottom line is that I'm willing to expend additional effort to compensate for my lack of the proper equipment and space. I know that rattle-can finishes are NOT ideal, but I'm hoping that as long as I can exercise enough care (hence this thread) I can manage to get an acceptable finish on it.
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Re: Finishing critique

Postby Steve Sawyer » Thu Jun 08, 2017 4:45 pm

Mike Conner wrote:My experience with Endurovar confirms that waiting 5 to 7 days for level sanding and buffing is needed to allow the finish to fully cure and shrink, and some of that finish shrinkage may be transport of the water absorbed into the wood surface.

I level and rough buff at 5 days, then finish buff at 10 days.

One way to monitor the curing progress is smell. EnduroVar has a distinct odor, sort of "sweet" and not the ammonia odor typical of most WB poly. I have a really good sense of smell and can sniff close to the curing surfaces. Most of the odor has faded by the 5th day.


Thanks, Mike. I'm using High Performance, not EnduroVar. I understand that EnduroVar has a slight ambering effect that I wasn't sure I could make work as a pigmented base and as a clear-coat. However, I would guess that your timing recommendations might apply to HP. Also, my sense of smell is notoriously bad, so I'll have to rely on your timing recommendations! :lol:
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Re: Finishing critique

Postby Barry Daniels » Thu Jun 08, 2017 8:10 pm

Reranch spray cans will put out as much overspray as a good HVLP gun will so the need for air exhaust is not diminished. You would probably be better off sticking to water-based spray or a wipe on.
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Re: Finishing critique

Postby Steve Sawyer » Thu Jun 08, 2017 10:35 pm

Barry Daniels wrote:Reranch spray cans will put out as much overspray as a good HVLP gun will so the need for air exhaust is not diminished. You would probably be better off sticking to water-based spray or a wipe on.

Yes, but it's summer - I can do this with the guitar body hung in the garage, or in the yard with a windbreak (provided the RH isn't too high). I'd do this all the time and not worry about having a place to spray if I lived in a more temperate climate! :roll:
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Re: Finishing critique

Postby Clay Schaeffer » Sat Jun 10, 2017 6:38 pm

You can get decent results with a $99 compressor and a $15 high pressure harbor freight jamb gun with a little practice. Guitars don't require either a high volume of air or a perfect "off the gun" finish - they are almost always leveled and buffed.
One thing you might try is using micron sand papers. The "grit" is more uniformly sized, so you don't get a few 80 grit sized particles mixed in with the 320 sized ones.
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