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Rattlecan Nitro finish problem. What is this?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=45471		 Page 1 of 1
Author:  Linus [ Wed Apr 01, 2015 2:28 pm ]
Post subject:  Rattlecan Nitro finish problem. What is this?
I'm doing a rattlecan nitro finish with products from ReRanch. It's a solid body with a maple top.

I'm getting a couple places near the edge of the guitar that look like bubbles but they are actually spots where the paint is NOT going. It's strange. It must be some sort of contaminant but I don't know what.

My method was to sand to 400 grit, wipe in a light shellac seal coat, then spray a couple coats of Amber nitro across the whole surface. Each day I've done a pass of brown around the edge to create the burst. There has been at least a day between coats.

Is this what people call "fisheye"? How do I fix this or at least keep it from happening again?

Here are two close up pictures.

Image

Image
Author:  WudWerkr [ Wed Apr 01, 2015 2:43 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
Looks like its been sprayed a little heavy to me . Its hard to tell in the picture, That could be fish eye . I tend to opt for thinner coats and more of them . When you sand are you using a Alum/Oxide paper or Sil/Carbide .. I have known of Sil/carbide leaving residue that contaminated the finish. It could also be that the paint your using is reacting to the Rattle can Laq. Then again I could be way off base idunno
Author:  Glen H [ Wed Apr 01, 2015 2:46 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
Those are fisheyes. Did you wipe it down with a clean rag with some naptha or similar to degrease it before spraying?
Author:  Linus [ Wed Apr 01, 2015 2:55 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
I didn't wipe it to degrease. Do you wipe with naphtha between coats or just before the first coat?

I tried to shoot light. The sunburst brown is a very light (not much color solids) nitro and its hard to shoot it lightly. The amber and black (hadn't shot the black yet) are thicker.
Author:  Greg B [ Wed Apr 01, 2015 3:00 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
Yep, them thar is fish-eyes. I agree that it looks like you're going a little heavy on the coats.

Also agree that the problem was no degreasing. I suspect there is some sort of residual grease or other contaminant from the wiping on shellac step. I usually just wet sand shellac sealer with some soapy water, but if the seal coat is very thin - at least use naptha and a rag. It isn't necessary between lacquer coats.

I've done a couple electrics with Reranch lacquer over a shellac base coat, and there haven't been any issues, so the recipe itself isn't a problem. However, IMHO a thin wiped coat of shellac isn't really a sufficient base. Either build it up enough to sand flat(ish), or use sanding sealer.
Author:  Cal Maier [ Wed Apr 01, 2015 8:37 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
Is this what people call "fisheye"? How do I fix this or at least keep it from happening again?

As mentioned before, yes those are fisheyes.
Because you're using rattle can lacquer you won't be able to fix them. If you were shooting from a spray gun you could add some fisheye eliminator to your mix and continue your spraying.

You will have to strip or sand back and start again.

You need to degrease using naptha or reducer before any finishing is undertaken.
Wipe the guitar thoroughly before sealing. Wipe again before starting your topcoats. This should be sufficient to achieve a fisheye free finish.

I agree with the others that your finish looks like it's going on heavy. Your pictures show quite a bit of orange-peel, but that maybe because of the lighting.

Good luck,
Cal
Author:  Glen H [ Wed Apr 01, 2015 9:14 pm ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
Linus, I wipe mine down with Naptha and a very clean rag, usually only on the first coats. A lot of things can cause fisheyes, but if it happens around the edges, I usually suspect fingerprints and contaminants on our hands from handling the instrument. A clean surface, equipment and shop will prevent them.
Author:  Joe Beaver [ Thu Apr 02, 2015 12:54 am ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
I have used rattle can nitro once on a non-guitar item. It did have some particularities about it. Nothing that severe though.

It looks to me like the problem only occurs in the areas where the amber nitro has been put down. I'm thinking the contamination came from the amber/nitro mix. Sprayed on to heavy, maybe during high RH? Was that a premixed spray? Was the base coat of shellac good quality degreased stuff?
Author:  philosofriend [ Thu Apr 02, 2015 7:00 am ]
Post subject:  Re: Rattlecan Nitro finish problem. What is this?
You have to get all the silicone (and grease) off before starting the finish. The fisheyes are usually from silicone which is mixed in car waxes, armorall, tire spray, boot waterproofer and who knows what else. If you were using a spray gun, you could get some "Smoothie" from an auto paint store (same as Stewart McDonalds "fisheye flowout"). You mix a drop with the lacquer, then no fisheyes. The downside is that you now have silicone evenly on the whole guitar and you have to keep using the Smoothie on every coat. The advantage is that it is a reliable fix. Trying to get all the silicone off before finishing can be really annoying. If you miss one tiny bit, BANG! Big ugly fisheye again!
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