Why those shiny patches may happen

[marylka]

Why those shiny patches in a painted area may happen .After several washes of color has been applied and you notice that an area is very shiny when the paint has dried .one of  the cause's  I can't stress this point enough.

When I open a new tube of  watercolor paint there is filler that comes out first ,in most cases this is gum Arabic.It happens with any brand of pigment.

It looks like clear jelly  substance this is common with a new tube at the beginning with some pigments  but should not continue with subsequent squeezing of pigment if so, it's faulty
 
I discard this excessive substance before I mix the paint ,if this concentration off gum Arabic is not removed and  remains in your mix, it causes the very shiny patch and bronzing damaging your work.

From my own experience I make sure I remove the jelly like substance when it is excessive, gum arabic/filler different brands may use other fillers.
Marylka

[marylka]

If i need to check a color before i place it on a painting in oils i use punched hole square  cut up from white plastic milk containers paint on it to check the color, then i can just throw it out .
 Marylka

[marylka]

When working with wet media acetate ensure that it is not handled as oil from the skin will not let the paint adhere .Pick up by the corner I would go as far as using cotton gloves when handling

 When buying  make sure the pads that it comes in is sealed less likely that it has been handled (I bought a single sheet to try and the assistant handled it it was useless)this was before i discovered the cause .I couldn't figure out why it repeled the paint until i saw the finger marks .
 Air brushing the color on is the best way to do it I don't have one so i paint it on Susan suggested adding ox gall to the paint I must try that the only reason I whant to do it as I need larger sizes then what the glazing viewer allows for backgrounds.

After it has been painted protect it in plastic sleeves as the paint will come off if it gets wet. This happens with yupo paper as well once handled it will become paint resist It was a great learning process .

Arleta Pech has a ready made available the thing is it's colors are what she usesfor her palette and the paint does not come off. I love it works well as it gives a sneek preview before you add the color to the painting or what color would be best.
 
I also thought there are coloured sheets of acetate available  in red, blue, yellow they would not be the same hue as what our pigments are but that  it would give a general color image.
Marylka

[mlsleisel]

A cause for concern, if you will.  First of all, I love your art and your paintings....and, like you, if have opened a tube of paint that has separated!  One tube was beyond help.  The other tubes have a "quick fix" - when you open the tube and see that the binder has separated from the pigment (I always do that now, because I use very little paint when I paint ACEOs so my paint doesn't get squeezed all that often!). Anyway, you can see the binder right near the cap opening. I close the tube again and gently begin to manipulate and squeeze the tube to "mix" the binder back in. Just squeeze the tube all over for a few minutes.  Your tube will look "awful" with all kinds of dents, but the pigment will mix back in with the binder!  My thoughts are that the manufacturer puts the binders in for a purpose and removing the separated binders may put "clean" paint back on your palette...but it may not be such a good thing for the paint...it may cause you to lose "the flow" of the paint and may cause you to lose the transparency we all love so much.....
If I remember my art history right, before modern day paints...the old school once used gum arabic in their final wash of their paintings to bring out the vibrancy and to protect the paint....Paint has come a long way from then...now the great paint manufacturers make show the paint has the gum arabic and honey and all such to make ALL the transparent paints very vibrant...hate to see this be lost! I may be wrong but I would advise not to remove the clear "goop!"

[mlsleisel]

This is what a friend (Laura Dicus) said about the shiny patch problem and the paint separation:


Actually it is better to remove the goo if it has separated in the tube and add a bit of diluted fresh gum arabic (1:10 - 1:20 G.A./distilled water) to the paint when you fill your well. The goo is gum arabic, which is the binder part of the paint formula. Before you re-close the tube use an eye-dropper to add a drop of the diluted G.A . This will protect the paint until it is opened again.

The separation occurs with paints that have large pigment particles or heavy particles and is inevitable. However due to environmental changes over time (heat/cold is the worst) the gum arabic can lose its solubility, become grainy and/or shiny when dry. When it has separated out of the formula it degrades a lot faster.

The milling process is as balanced and sensitive as the paint's chemical formula is. You are more likely to retain the paint's (consistent) performance if you do your re-mixing in the well rather than in the tube. Do a test before using the paint on your actual work. If a medium wash dries shiny (bronzes) there is too much G.A. Simply add more pigment and test again.

Manipulating the tubes can also weaken the metal even if dents don't develop. Pressure can also increase if the paint batch was not properly cured. (Ever have paint come shooting out of the tube when you open it? No fun!) Tube paint isn't formulated to dry/wet/dry/wet like pan paints are. While it is possible to reconstitute old dried paint with the proper ingredients and tools taking a risk that a small crack or weak point in the bottom seal will develop is usually not the affordable solution.

Signed,
"Fascinated With Pigment and Paint Properties"
 
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[marylka]

A cause for concern, if you will.  First of all, I love your art and your paintings....and, like you, if have opened a tube of paint that has separated!  One tube was beyond help.  The other tubes have a "quick fix" - when you open the tube and see that the binder has separated from the pigment (I always do that now, because I use very little paint when I paint ACEOs so my paint doesn't get squeezed all that often!). Anyway, you can see the binder right near the cap opening. I close the tube again and gently begin to manipulate and squeeze the tube to "mix" the binder back in. Just squeeze the tube all over for a few minutes.  Your tube will look "awful" with all kinds of dents, but the pigment will mix back in with the binder!  My thoughts are that the manufacturer puts the binders in for a purpose and removing the separated binders may put "clean" paint back on your palette...but it may not be such a good thing for the paint...it may cause you to lose "the flow" of the paint and may cause you to lose the transparency we all love so much.....
If I remember my art history right, before modern day paints...the old school once used gum arabic in their final wash of their paintings to bring out the vibrancy and to protect the paint....Paint has come a long way from then...now the great paint manufacturers make show the paint has the gum arabic and honey and all such to make ALL the transparent paints very vibrant...hate to see this be lost! I may be wrong but I would advise not to remove the clear "goop!"

Hi and welcome I believe if the "goop" is not removed with that much gum arabic mixed into a tiny amount of pigment I get a hard shiny surface it's as if I have brushed it with a mix of gum arabic when I finished a painting to give it a high gloss finish.I do leave some of it in I do remove the excess,I find in working the tube when small to be almost impossible.The best way may be to empty the tube in a small container and mix it in.Laura has visited this forum and mentioned that was i was describing was excessive .Thank you I'm happy you like my art.
Marylka

[Renee]

This goop is from hanging on a shelf to long and the pigment settling. Or the tube on its side. The pigment is heavier than the binder and other ingredients so it goes to the bottom of the tube or the lowest part of the tube. Even if your tube is setting sideways in a drawer, the gum will run to the end that is raised the most  if it sets that way long enough. It was mixed perfectly before the tube was filled. It really is not excess gum. It's gum that was meant to be in the formula. Because of this I shift my paint around in different positions every time I get into them. But sometimes they come off the rack with the goop at one end.
In this case, I will dump the whole thing in a little crock well and mix with a tooth pick and let it dry. If I want to use it, I will put a little water on the top and let it soak. Then dump my soft paint into my painting palette. I use my paint as needed this way. But if the paint is fine, I leave it in the tube.
 I know of people who tried this squishing the tube thing and sometimes the tube will pop open and paint all over.
There is nothing wrong with removing the goop at the top of the lid area because if your paint seems to need a little gum farther down the tube, you can add that every time you squeeze paint into your palette.