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Don Noon

Beady eyes... extreme version of fisheye

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After cooking up a new 1:1 varnish with cooked burgundy resin, and thinning it out quite a bit (~30%) with various things which shall for the moment remain nameless, I tested it out, as usual, on glass and wood.  The first application on wood sunk in as expected; the second coat would have nothing to do with its older brother, and gathered up into little beads.  Interesting, but not very useful.  

Theoretically, I don't quite understand the mechanics of how this works.  Certainly there is a high surface tension of the wet varnish that makes it gather, but I don't quite get the mechanics of wetting, or in this case, not wetting.  And maybe self-leveling is related, in that (presumably) high surface tension is needed for self leveling (?)  Probably mostly related to the solvents though.

Anyone mess around with the fisheye eliminator additives for oil varnish?  I don't even know if they  work with oil varnish.  Experiences with various solvents?

5a086d4341d1e_Beadyeyes.JPG.9b0b074b027a983bcb6a1c10a0cd4c06.JPG

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Have you used the "various things" in the past?  No chance of any silicon or teflon contamination?  I'm sorry I can't be of help but I'll watch the post and good luck Don!

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Have you tried adding a little acetone or xylene to your second coat to "cut" the surface of the underlying varnish?

What does more mechanical action do... brushing in vigorously?

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Intuitively, I would try warming the varnish.  You might also prep the previous layer with turps or turps and a bit of oil.  Artists used to leave their under painting to dry for a long period before proceeding, and then prepped the underpainting with a thin layer of oil well rubbed in.

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Hi Don, just my opinion, adding a solvent to spread that stuff will ultimately give you a crackle finish when it leaves the mix. It looks like there is total surface tension and no surface adhesion, like water on a duck's back.  fred

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I think what happened is that after the first coat vented off one of the solvents remained as a contaminant as it were. There may have been a micro-thin film left over. The second coat with the original mix of solvents would then have a different surface tension; it becomes immiscible as it were with the dried varnish. I saw this with spike lavender added to my varnish that also had turpentine.

I suspect that it is not good chemistry to mix solvents. When I have time I will run some tests on this idea.

Stay Tuned.

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8 hours ago, Thomas Coleman said:

Have you used the "various things" in the past?  No chance of any silicon or teflon contamination? 

8 hours ago, David Burgess said:

Have you tried adding a little acetone or xylene to your second coat to "cut" the surface of the underlying varnish?

What does more mechanical action do... brushing in vigorously?

7 hours ago, Addie said:

You might also prep the previous layer with turps or turps and a bit of oil. 

2 hours ago, FredN said:

Hi Don, just my opinion, adding a solvent to spread that stuff will ultimately give you a crackle finish when it leaves the mix. It looks like there is total surface tension and no surface adhesion, like water on a duck's back.  fred

There is one new solvent in the mix that I haven't used before, and that could be the culprit.  No silicone, teflon, or wax anywhere.

There is 5% xylene as one solvent.  I didn't brush, but used a finger... and rubbed it in very hard when I saw it immediately beading up.  Didn't help.

Interesting idea about using a thin pre-wetting turp/oil coat.  I'll see if that works.

I have never had crackle problems in the past, although there is that one new solvent in there.  Can't possibly crackle if it just sits there in little beads, though, and definitely is a high tension/no wetting problem.

The idea of the multiple solvents is to use thin, volatile ones to help filter and spread the varnish, and slower-evaporating ones to keep it from getting too sticky too quickly, and give it more working time.  I also have this tendency to use a little bit of everything, just 'cuz I have it... although I have some turpentine and didn't use any of that.

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54 minutes ago, Don Noon said:

There is 5% xylene as one solvent.  I didn't brush, but used a finger... and rubbed it in very hard when I saw it immediately beading up.  Didn't help.

I know that you are very knowledgeable in general, but please take care of yourself.  Personally, I wouldn't touch xylene with my bare finger.  The quantities may be small, but I err on the side of caution; we only get one body and brain, and they have to last....

https://en.wikipedia.org/wiki/Xylene#Safety

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I haven't experimented with it, but isn't ox gall a traditional wetting agent for artists?  Don't know if there might be some way use it in your case.

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Ummmm.......could the first coat have very effectively sealed the surface, and cross-linked indissolubly like some finishes do, thereby giving the second coat nothing to cling to, and no place to go?

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I have mostly encountered fisheye in painting metal, and prevent it by preheating the object before painting.  Since preheating a violin isn't practical, I suggested warming the varnish.  It might help, or it might not.

Ultimately, I think we all know the solution, but nobody wants to say it: file under 'r' for "reject."  <_<

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I tried a simple test with a variety of solvents, just putting a drop onto a varnished surface and observing whether the drop wanted to spread out or stay in place.  The results were somewhat surprising.

Acetone, xylene, and my new "solvent who shall remain nameless" all tended to just stay put and not spread out... poor wetting.  I expected the thin solvents to wet better.

Other solvents or liquids that didn't wet well included lacquer thinner,  lamp oil, linseed oil, old Recochem turpentine, and oxidized turpentine... although most of these have high viscosity, and might spread out given more time.  The "old turpentine" is several years old, kept in a glass bottle, with a lot of obvious white precipitate on the bottom (which is part of why I have been reluctant to use turpentine).

There were just a few solvents that wet well and spread out:  mineral spirits, "turpatine" (Klean Strip, from Home Depot), and lavender oil (fairly viscous and slow).  I'm still curious about the commercial "fisheye eliminator" additives, and will get some to see what it might do.  Ox gall I'm not sure is compatible with oil varnish; looks more like it's for water or alcohol use, and generally looks like scary uncertain organic stuff.

So, bottom line is that most of the solvents I used to thin my varnish were wetting-challenged when it comes to applying to dried oil varnish.  I'll try cooking out all that stuff, and re-thin with the ones that tested out with better wetting.

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10 hours ago, Don Noon said:

Anyone mess around with the fisheye eliminator additives for oil varnish?  I don't even know if they  work with oil varnish.

I never used a fisheye eliminator with oil varnish, but I do use it in refinishing with nitrocellulose lacquer (on pianos) when needed.

The photo shows basically the opposite of a fisheye, though, so I doubt that fisheye eliminator will work. 

Basically, a fisheye is an area of finish that has been unevenly contaminated with silicone (typically in a furniture polish), causing a lower viscosity spot which ends up sinking below the rest of the lacquered surface when dry.  A fisheye is a dip, not a bead.  My understanding is that fisheye elimator works by adding a small amount of silicone (and possibly other chemicals) to even out the viscosity of the finish, thereby allowing it to dry to a uniform depth of coat once the solvents evaporate.  Once you add fisheye eliminator to a finish, the general idea is that you must use it in every additional coat (whether now or in 50 years), or the fisheye problem will most likely come back and be worse than it originally was.

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How long was the burgundy cook? I ask because this past summer I cooked quite a bit of Black Spruce for color, noticed that a real long cook left me with something insoluble in alcohol and a varnish made of this did a similar thing, beading, reducing the color cooked rosin to an additive of a regular rosin oil varnish,seems to have smoothed things out. Not using any solvents, just hot mixing linseed to thin to a workable consistency. 

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Yup stay away from fisheye eliminators. Joe DeF has is it correct about them. Once you start down that path it would be difficult to control in your shop. 

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10 hours ago, James M. Jones said:

How long was the burgundy cook? I ask because this past summer I cooked quite a bit of Black Spruce for color, noticed that a real long cook left me with something insoluble in alcohol and a varnish made of this did a similar thing, beading, reducing the color cooked rosin to an additive of a regular rosin oil varnish,seems to have smoothed things out. Not using any solvents, just hot mixing linseed to thin to a workable consistency. 

I see this too, Mike, with cooked rosin, but in this case, I am pretty sure the issue is the solvent. I had this beading with an uncooked rosin varnish. 

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11 hours ago, Violadamore said:

Ummmm.......could the first coat have very effectively sealed the surface, and cross-linked indissolubly like some finishes do, thereby giving the second coat nothing to cling to, and no place to go?

Right, but it is normal for dried (cured) varnish to accept a second coat without beading. In this case, I think the unevaporated solvents make the difference. 

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11 hours ago, Don Noon said:

I expected the thin solvents to wet better.

1

Me too, but I am pretty sure that surface tension is independent of viscosity. Furthermore, as Violadamore said, the surface properties of the dried varnish come into play too. 

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49 minutes ago, HoGo said:

Did you try to apply it over another dry varnish?

The photo of the beading is over the same varnish, dried.  I also applied it over another rosin varnish, and it was even worse... if such a thing is possible.  Actually, it was just quicker about gathering up, since you really can't get more beady than the one I showed.

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29 minutes ago, Don Noon said:

The photo of the beading is over the same varnish, dried.  I also applied it over another rosin varnish, and it was even worse... if such a thing is possible.  Actually, it was just quicker about gathering up, since you really can't get more beady than the one I showed.

Wow, really a beading nightmare!! Never seen anything like that.

Maybe your secretive solvent has left a veil over the dried varnish (the effect looks like silicone or paraffin) or the amount of solvent you used for your second coat was really excessive intrinsically to the properties of altering the surface tension of that solvent.

That's why I hate solvents in oil varnish and try to avoid them as much as possible......too many unknowns and too many unpleasant surprises<_<

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The fact that the varnish beaded up more quickly on a dried varnish sample that didn't use the mystery solvent leads me to believe that it's the non-wetting action in the fluid varnish that's the problem.  Plus...

I cooked out the solvents at ~200C and replaced them with a mix of the good-wetting solvents listed earlier.  Applied over dried varnish, there is no beading or fisheyes.  

In aerospace bonding, there is a "break test" to see if a surface is clean, by applying a liquid and seeing if it beads up or wets and flows out.  So I think this has proven to my satisfaction that the concept of wetting applies well to varnishing, to test the materials and see if they wet or not on a dried varnish sample.  It was also perhaps important to note that an old batch of turpentine didn't wet well... at least it would be a good test for seeing if you should use that turpentine or not... but I'd also worry that the wetting properties of the turpentine in the varnish might change over time.

Another lesson is that a great solvent isn't necessarily a good wetting agent, and can in fact be horrid.

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Good "wetting" is often achieved by sufficient mechanical manipulation. Learned that many years ago, with both epoxy and polyester resin bonding. If epoxy tends to roll off the surface during spreading, rather than smearing, you have not yet gooshed it around enough to achieve a good bond.

But it sounds like your "mystery solvent" was the biggest problem. I mostly use solvents which have a great track record in the OEM automotive paint industry (individually and in combination), since that's one area where there are huge consequences for getting it wrong.

I haven't used any "eye of newt" type solvents for at least 30 years, and have no regrets about that so far.

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