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Dominik Tomasek

Oil varnish sweating

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15 minutes ago, Dominik Tomasek said:

From your describtion it seems that the problem could be the matter of not giving the varnish enough time to dry. The bumps really are sort of blisters or something. 

Thank you for your advice. 

I'm not seeing them as air-entrained blisters, since those tend to appear more whitish, due to the severe refractive index changes between air and varnish.

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12 minutes ago, David Burgess said:

I'm not seeing them as air-entrained blisters, since those tend to appear more whitish, due to the severe refractive index changes between air and varnish.

Well, let's check that! If I understand that clearly, to ensure that the blisters are produced by gases they should be empty inside, filled with air, am I right?

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9 minutes ago, Dominik Tomasek said:

Well, let's check that! If I understand that clearly, to ensure that the blisters are produced by gases they should be empty inside, filled with air, am I right?

Internet diagnosis can be really difficult. Next time I am in the Czech Republic (which I don't expect to be really soon), I'd be happy to get together with you, and we could probably nail this down in 15 minutes or less.

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7 minutes ago, David Burgess said:

Internet diagnosis can be really difficult. Next time I am in the Czech Republic (which I don't expect to be really soon), I'd be happy to get together with you, and we could probably nail this down in 15 minutes or less.

Hahah, I see, that would be the easiest way to solve all these problems I have. Sorry for being so confusing - this is my first time varnishing and as you can see I am still not completely sure what I am doing! 

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6 hours ago, Dominik Tomasek said:

Isn't there any risk of combining oil varnish and spirit thinne shellac? 

No not at all as long as the shellac is wax free...shellac acts as a barrier coat....to truly understand varnishing you must understand using dissimiliar bases , the whys , whens and hows....

think of these varnish coats as sheets of plastic with trapped gas, the gas must leave before another is applied, if you coat too soon with the same base you just put another film over a film with trapped gas, and rewet the pores,the shellac, because it is not the same base {alc} vs turp, will not reload the pores with the same solvent, it will be a sheet with a solvent the evaporates out very quickly and act as a barrier for the next oil coat....but that coat must be very dry

again follow David [and my} advice and always do a varnish system {all coats} on a substantial piece of scrap to make sure that every thing works well together....if it does it on scrap, it will do it on the violin...

As I'm sure by now you can see the logic of if you were to see this on scrap, you probably would not have said "oh that looks great" and then applied it to the work...

if it makes you feel any better, people [such as myself} can have years of experience with varnish and still get thrown for loops, have problems, need to redo stuff, on and on....so don't feel too bad, just experiment on scrap, its less painful that way...

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In examining your pictures, it is clear to me that the last coat of varnish did not stick to the previous coat.  There is some contamination on the surface.  Those clumps of varnish are what you get when the varnish does not stick but the surface tension (as it dries) pulls the wet varnish back into a ball.  

Is the varnish the problem or some surface treatment you gave the previous varnish coat--well, we are not going to be able to determine that.  You are going to have to do that.  Run some tests.  All it takes to get into trouble is to use a polish or lubricant on the varnish coat before putting the next coat on (and this polish or lubricant contains silicones).  This is a well-known problem in the business of finishing. 

There are also products that you can add  to the varnish to help it wet the surface (fisheye preventer??).

Shellac is your friend.  

Mike D

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Adhesion.  It isn't working for me. Nothing seems to be lately. The varnish I thought came out good, can come off right to the bare wood with just a clamp.  The other one that has a myriad of errors, but still somehow looks kind of cool, at least to me, (certainly not the bowling ball smooth stuff, I'VE NEVER ACHIEVED THAT EVER, I'm not sure that I even like that sort of finish on a violin. Kinda boring unless you can see a lot of different colors.)  

Even that one, after gluing a fingerboard on, I saw a thin layer of glue, no bigger than an eraser tip on a pencil that was loose on one edge, and was pulling up the varnish to bare wood.  How did the glue even get on the belly in the first place?  How did the one edge get pulled up?

I've had problems before, but nothing even close to what I've had in the last few months.  Usually just roughness that I didn't have the sense to sand smooth.  Really.  I'm not too bright sometimes. 

Now my problems seem to be the result of smoothing out.  It looks good until I try to smooth it out. I don't push hard on it, at least with the sandpaper. I use a pink rubber eraser as my backer. I've only used water, and not oil to eliminate that problem. I used pumice and Tripoli with a chamois, and 3M 800 wet/dry that I don't think has stearates, on it.  (Why in the world would anyone put stearates (computer doesn't like that word) on sandpaper.  It just seems stupid.)

I even have to make a new peg, I had all the pegs in a bag, with the strings and tailpiece, and there are only 3.  Nothing is going right.  Vanish is just one piece that isn't working lately.

I guess this doesn't really fit the title.  I don't get frustrated very easily.  I'm getting close.

Ken

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Hi David,  regards heat reducing acidity, hardening- I've attached a small statement on heating rosin. The chapter has more on the subject but you have to be an organic chemist to understand it. Just heating to melt and exposing to air increases melting point.  fred 

 

 

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2 hours ago, David Burgess said:

Ken, that's pretty much the way it goes. What the heck ever made you think you wanted to make violins? :lol:

That, and I don't see details very well.  They sound good.  I'm going to do an Archtop guitar.  Bigger, but more details, and fancier varnish.  Isn't that a step in the WRONG direction?  But it is for me, so as long as it plays good.

It's fun to do though.  I like planning the best. And getting them done in the white.  I could be an apprentice, doing the grunt work.  Let the pro finish it up.  The pro part in me is lacking.

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1 hour ago, David Burgess said:

Fred, I see some things in your document about heating increasing solubility and changing color, but nothing about it reducing acidity.

There is spoken about the addition of soda or lime, both should be able to reduce acidity. However why should acids be reduced at all, is there a general reason ? 

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On 1/6/2019 at 6:13 AM, Dominik Tomasek said:

Dear Maestronetters,

I have absolutely no idea whether "sweating" is relevant verb thus I am including some photographs. 

I have got this problem with my oil varnish - after it is applied it creates sort of tears, drops, lakes. My varnishing process is following - I prepare the surface, apply gelatine, than thin ground coat of my oil varnish (colophony, turpentine, linseed oil, lime), after it is dry I apply thin coat of artists' oil paint (colourant) and after the paint is dry I apply another coats of my cooked varnish. And then the problem begins. 

What could be wrong? I understand that some ingredient is drying faster than the other but why would it happen when the artists' paint is completely dry (even for several years)? 

Thank you in advance! 

Dominik

IMG_20190106_145718.jpg

IMG_20190106_145713.jpg

IMG_20190106_145734.jpg

IMG_20190106_145849.jpg

to further point out my hypothesis, if we look closely at the first pic that is showing the blisters, we see that every single one of them is either on the more open porous spring growth line/delineation,or right next to a line,... and the effect on the back as the maple has different grain than the front, it is showing as more of an uneven orange peel'ish texture , some of which seems to be from application, and some from the under coat being not quite dry...imo

but the top with every little bubble, bead, whatever you would like to call it, is on a line, which adds some evidence to my summary....for what its worth.

IMO, inadequate dry times are a very common culprit in varnish problems, particularly with turpentine solvent based varnish, turpentine itself has the ability to REALLY soak into wood pores and stay wet for quite some time, thus wanting to off gas , which puts an exclamation point on the need for a proper ground coat that seals the wood with a dissimiliar base that will hopefully seal over the pores and not be resolventable based on being of a different base...

beyond the dry times being pushed too close for recoating, the gelatin coat was most likely to thin and thus not that monolithic, which allows the following turp based varnish to fall into the pores...

also, by applying the coat too soon to the first varnish coat, which may feel hand dry, it is only skinned and the second coat will resolvent the under coat and give the effect that is seen on the back, which is all the more reason to rely on your nose to tell you when something is dry rather than your hand.

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9 hours ago, jezzupe said:

to further point out my hypothesis, if we look closely at the first pic that is showing the blisters, we see that every single one of them is either on the more open porous spring growth line/delineation,or right next to a line,... and the effect on the back as the maple has different grain than the front, it is showing as more of an uneven orange peel'ish texture , some of which seems to be from application, and some from the under coat being not quite dry...imo

but the top with every little bubble, bead, whatever you would like to call it, is on a line, which adds some evidence to my summary....for what its worth.

IMO, inadequate dry times are a very common culprit in varnish problems, particularly with turpentine solvent based varnish, turpentine itself has the ability to REALLY soak into wood pores and stay wet for quite some time, thus wanting to off gas , which puts an exclamation point on the need for a proper ground coat that seals the wood with a dissimiliar base that will hopefully seal over the pores and not be resolventable based on being of a different base...

beyond the dry times being pushed too close for recoating, the gelatin coat was most likely to thin and thus not that monolithic, which allows the following turp based varnish to fall into the pores...

also, by applying the coat too soon to the first varnish coat, which may feel hand dry, it is only skinned and the second coat will resolvent the under coat and give the effect that is seen on the back, which is all the more reason to rely on your nose to tell you when something is dry rather than your hand.

Dear jezzupe,

thanks. Now I also do think that the probles is caused by not giving the varnish proper time to cure. It does not seem to be caused by the colourant as this would appear right after the first coat. 

I'll run some tests as others advice me and I will see. Also I will kepp updating this topic if needed. 

Thanky you all! 

Dominik 

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Dominic- you won't know the cause until you repeat the making and cook out all the water out of the resin before you add oil.  Use a commercial Boiled oil, not raw to shorten the cook time to string, then use some good oil when you've got  out the problems. I would not smear a colorant on the inst, if it is a  raw oil mixed with the pigment it would take weeks? for it to dry laying on the bench. If you want to color the varnish squeeze  around 1/4 inch  or more of Ochre, Sienna or Umber into the mix, cook around 350oF ( ca 10 hrs) to an almost tackless bead on glass or  to a 12-14 inch string ( when a drip on glass makes a round dome the cook is done). A drip on glass shows the bead keeps getting darker over time, and has to be dead black at the end to have  good color when thinned. My varnish mix is around 12g oil to 15g resin. You lose around 15% resin, so the ratio is ca !:1 at the end. Add lime before oil is added, heat resin to ca 400oF and add 5-6% lime, cook for a few minutes and then add oil. As some have mentioned, have your lucky charm nearby.  fred

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15 hours ago, Dominik Tomasek said:

Dear jezzupe,

thanks. Now I also do think that the probles is caused by not giving the varnish proper time to cure. It does not seem to be caused by the colourant as this would appear right after the first coat. 

I'll run some tests as others advice me and I will see. Also I will kepp updating this topic if needed. 

Thanky you all! 

Dominik 

remember, sniff the violin but don't smell the glove....in general atmospheric conditions during winter can be damper and things can take longer to dry, are you in a damp shop, or a controlled shop? these things make a difference, varnish dries different in damp cold air than it does in dry hot air....also too much direct heat can make a varnish that was drying ok start to not dry ok and form bubbles . there is a degree and amount that a varnish in a pore can be dry/damp before it becomes a problem, a pore that had a wee bit of sticky varnish in it may over coat fine, only to start rapid hot air ballooning evaporation if heat is applied... so use of uv lights must be measured as well, they speed/are needed to aid drying, but can cause problems if used wrong, basically heating the wood too much and causing evaporation...

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On 1/13/2019 at 9:09 AM, Ken_N said:

Adhesion.  It isn't working for me. Nothing seems to be lately. The varnish I thought came out good, can come off right to the bare wood with just a clamp.  Vanish is just one piece that isn't working lately.

I guess this doesn't really fit the title.  I don't get frustrated very easily.  I'm getting close.

Ken

Ken, Ken, Ken.  What are we to do?

  If I weren't familiar with being a painter I wouldn't have a comment for you, so here's the grain of salt comment for this subject of finishing.  First, as per handling a freshly, varnished fiddle,  I wouldn't even touch it until the six week mark using store bought canned or even touch it at the eight to nine week mark using my own concoctions.  The thumb print test works for me.

  A through read thru of Heron-Allen varnish and varnish making chapters for a period of a few years may enlighten you some.  One doesn't have to do what he writes, just sort of figure out where and what he's alluding too.  Notice I mention to read for a few years, not weeks.  This subject takes awhile to learn on your own.  Studying Fred and K.G., Johnston etc. won't hurt either. 

Patience and understanding is a must.  Too much time has already gone by to be not getting this stuff right though I'll add my work is far from perfect assuming I understand what the word perfect should mean. 

I mention Heron-Allen.  What else do you have to lose?  You've tried almost everything else Sir.

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Uncle,

Yes, I know Strad told a customer that the varnish wasn't dry yet.  But it just seems dry.  I promise I'll wait from now on.  I did find that the other one came out the exact color and look that I was going for; at least on the back; and has a funky, Montagnana crinkle to it, from the last thick coat that I put down hoping to cover up holes that didn't exist before.  Not quite a brilliant idea?  It's a Gofriller model, so it's a Venetian trait; right?  "Varnish them fast, we have more to make!"

Yeah, I'm sure I can polish it down. 

In a couple of months.

Ken

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