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Author Topic: Yikes! White dot patterns on finished canvas  (Read 2450 times)

SallyG

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Yikes! White dot patterns on finished canvas
« on: March 28, 2010, 12:15:59 am »

I'm using Premier Eco Print Shield -- rolling it on. 2 coats glossy, final coat matte. I've had success with it in the past. Suddenly, I'm now getting patterns of tiny white dots. (Please see attached JPEG.) I'm trying to figure out what is causing it. Am I not putting on enough coating or too much or rolling it incorrectly? I have changed to 8" rollers recently, that I bought at Home Depot, but they are identical to the high density, ultra smooth, foam 4" rollers that I had gotten from Premier.

[attachment=21107:dots_on_...d_canvas.JPG]

I'm installing my next exhibit this Thursday, and I have one more 44" x 6' canvas yet to do, plus two smaller ones. I need to figure this out right away.

Any ideas/suggestions could be a life saver.

Thanks, Sally
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Colorwave

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Yikes! White dot patterns on finished canvas
« Reply #1 on: March 28, 2010, 12:47:00 am »

I use a different water base coating, but to me that just looks like an acrylic coating that hasn't fully dried or cured.  Have you tried force drying to make sure that the whiteness doesn't go away over time?  It doesn't look like specks of talc that are used as a flattening agent in satin and matte finishes.  If the flattening agent was settled out you would see spots, but they would most likely be smaller, and would certainly show up when wet.  I'm assuming that these only show up as it dries, right?  If you want to test another approach, I'd try a little thinner material.  Not applying less with the roller, necessarily, but more water in the mix.  You need to make sure that you have a wet enough application for it to level itself out.  You can always apply another coat, if it needs it.  Best of luck solving this.  Deadlines can certainly suck when you have a complication to sort out.
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dgberg

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Yikes! White dot patterns on finished canvas
« Reply #2 on: March 28, 2010, 06:05:23 am »

How did this material look as it was going on? Did you see the tiny spots as soon as you put the first coat on? Were these small defects ever small air bubbles? If you take your finger and rub one of the small specks does it dissolve or come off the print as a small bit of heavy varnish? Did this product ever freeze in shipping over the winter. Lastly if you take a very fine paint strainer(Available at Sherwin Williams) and pour your liquid through it do these particles seperate out.
What I am trying to determine here is if you have suspended particles in the material and and when is the firstpoint it shows up in the process?
« Last Edit: March 28, 2010, 06:08:12 am by Dan Berg »
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SallyG

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Yikes! White dot patterns on finished canvas
« Reply #3 on: March 28, 2010, 02:53:37 pm »

Quote from: Dan Berg
How did this material look as it was going on? Did you see the tiny spots as soon as you put the first coat on? Were these small defects ever small air bubbles? If you take your finger and rub one of the small specks does it dissolve or come off the print as a small bit of heavy varnish? Did this product ever freeze in shipping over the winter. Lastly if you take a very fine paint strainer(Available at Sherwin Williams) and pour your liquid through it do these particles seperate out.
What I am trying to determine here is if you have suspended particles in the material and and when is the firstpoint it shows up in the process?
I've tried wetting and rubbing away the dots. No luck.

The strainer sounds like a good idea. I'll be trying that shortly.

I'm also going to do a test coating, using the original 4" rollers on one side and the newer 8" rollers on the other, and see if that makes any difference.

I'll let you know how it goes.

Thanks, Sally
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dgberg

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Yikes! White dot patterns on finished canvas
« Reply #4 on: March 29, 2010, 05:17:55 am »

Sally,
I probably wasn't clear. The little test you did,I mean't when it's wet. With a clean canvas. You start applying the material with the roller. How soon after you start the application do you start seeing the dots? If it is wet and you lightly slide your finger over one of these. Is it something in the finish that wipes off? Probably can only be one of two things,an air bubble which would not dry like it did. Or pieces of something that have seperated in the finish that don't belong there.

SallyG

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Yikes! White dot patterns on finished canvas
« Reply #5 on: March 29, 2010, 10:56:15 am »

Quote from: Dan Berg
Sally,
I probably wasn't clear. The little test you did,I mean't when it's wet. With a clean canvas. You start applying the material with the roller. How soon after you start the application do you start seeing the dots? If it is wet and you lightly slide your finger over one of these. Is it something in the finish that wipes off? Probably can only be one of two things,an air bubble which would not dry like it did. Or pieces of something that have seperated in the finish that don't belong there.
I do see air bubbles when it's wet. I don't see any particles. I'm wondering if I'm rolling it too much, tryiing to even out the coating.

Sally
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dgberg

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Yikes! White dot patterns on finished canvas
« Reply #6 on: March 29, 2010, 12:15:40 pm »

Air bubbles usually come from putting too much materials on at one time. The canvas is very porous and air can get trapped and cause a bubble if you load on too much material at one time. Sounds like you have done this quite a bit so I do not want to go through the speech as we say. Watch the Breathing Color video for Glamor II,good stuff. Put the first coat on and don't overroll. I have had more of an issue with the pin holes(Material soaking in at one spot) then bubbles.
Keep at it ,sounds like your on your way to fixing it .
« Last Edit: March 29, 2010, 12:16:46 pm by Dan Berg »
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SallyG

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Yikes! White dot patterns on finished canvas
« Reply #7 on: March 29, 2010, 02:11:38 pm »

Quote from: Dan Berg
Air bubbles usually come from putting too much materials on at one time. The canvas is very porous and air can get trapped and cause a bubble if you load on too much material at one time. Sounds like you have done this quite a bit so I do not want to go through the speech as we say. Watch the Breathing Color video for Glamor II,good stuff. Put the first coat on and don't overroll. I have had more of an issue with the pin holes(Material soaking in at one spot) then bubbles.
Keep at it ,sounds like your on your way to fixing it .
That video was quite interesting, and a very different technique from the videos for Premier Art EcoShield, which is what I'm using. I wonder if the difference between the varnish of Breathing Color and the water-based finish of Premier Art would make a difference in the technique, or should I try the pooling technique shown in the Breathing Color video. Too much information. I was doing better when I didn't know as much. Sigh.

Sally
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Colorwave

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Yikes! White dot patterns on finished canvas
« Reply #8 on: March 29, 2010, 04:30:35 pm »

Sally-
Don't be thrown by the word varnish, as is is a broad and somewhat ambiguous term, not unlike the word enamel.  Although it has traditionally been associated with solvent dispersed coatings, it does not need to be solvent based necessarily.  Both products are water based.  I am certain that the Glamour II is an acrylic polymer, and since almost water based clear finishes for fine art are, I would assume the same for the Premier product.  Believe it or not, all water based coatings and paints still have trace amounts of VOCs, some form of solvent, but that is only an aside, and not relevant here.  I think the concepts on the BC video should apply for any water based finish on canvas, assuming that there are no issues with the water fastness of your ink/canvas combination.  I print with an HP that typically is highly water resistant on canvas, but have tried one fine art canvas that would not allow the puddle technique for rolling, as the ink did not have a very good bond to the canvas.  Your spots still look awfully big to me to be caused by air bubbles, but I suppose it is possible.
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SallyG

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Yikes! White dot patterns on finished canvas
« Reply #9 on: March 29, 2010, 04:47:37 pm »

Quote from: Colorwave
Sally-
Don't be thrown by the word varnish, as is is a broad and somewhat ambiguous term, not unlike the word enamel.  Although it has traditionally been associated with solvent dispersed coatings, it does not need to be solvent based necessarily.  Both products are water based.  I am certain that the Glamour II is an acrylic polymer, and since almost water based clear finishes for fine art are, I would assume the same for the Premier product.  Believe it or not, all water based coatings and paints still have trace amounts of VOCs, some form of solvent, but that is only an aside, and not relevant here.  I think the concepts on the BC video should apply for any water based finish on canvas, assuming that there are no issues with the water fastness of your ink/canvas combination.  I print with an HP that typically is highly water resistant on canvas, but have tried one fine art canvas that would not allow the puddle technique for rolling, as the ink did not have a very good bond to the canvas.  Your spots still look awfully big to me to be caused by air bubbles, but I suppose it is possible.
Thanks for all the information. I'm definitely not seeing the dots in the gloss finish -- only after the matte coating. I'm going to try opening a new bottle of matte and see if that helps.

Thank you, Sally
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Colorwave

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Yikes! White dot patterns on finished canvas
« Reply #10 on: March 29, 2010, 04:55:06 pm »

Then it must be the flattening agent, which is a powdered component (usually talc) that can settle out and clot.  Copious stirring and a good strain and you should have it solved.  Paper strainers with fine mesh are usually the best, but you can use multiple layers of cheesecloth or some pantyhose if you are in a pinch.
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k_p98

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Yikes! White dot patterns on finished canvas
« Reply #11 on: March 31, 2010, 11:47:04 am »

Kind of late to the party here Sally, but using Eco Print Shield myself, I wanted to share what I have learned.  

It has been quite a struggle for me to get it just right.  I first bought a quart of the satin, played around a bit, and thought I had something good.  I tried different concentrations of dilution and lots of different rolling teqhniques.  When I bought a gallon of the matte, things really started to go downhill.  The matte really is quite ugly stuff in that it not only dulls the prints, but actually leaves a milky coating.  The trick of course was to mix.  Wanting to use up the huge gallon jug I had of matte, I bought a quart of gloss.  So now I am getting fairly consistent results with mixing 1/2 matte, 1/2 gloss, and to that add 20% distilled water.

Now as for rolling this was a bigger issue.  I won't bore you wit the details of how I got here, but this is how I do it.  First of all, I have foamboard hanging on the wall.  On top of this is a layer of thin brown kraft paper that is actually coated on one side and hence slightly water resistant.  On top of this I have tape folded over running along the top edge.  The point of doing this is to prevent little hairs and debris from getting on the print.  If you have a workshop you might be good, but I was doing all of my rolling on the foamboard that was laying on my carpet, and you can imagine how dust was getting all over the print.  The canvas is nicely taped to the kraft paper and just hangs on the wall, waiting for coating.

Now with the coating, I wouldn't say I do anything special to get it on.  I actually don't use one of those painter pans for the roller.  Instead, my foam roller brush lives in a jar, with the hole to insert the handle pointing up.  The jar is always at least 1/2 to 2/3 full of the Eco Print Shield mixture.  I do this because washing out the foam is such a waste.  This stuff is very expensive so I was looking for a way to make sure 90% of it gets on the print and doesn't go down the drain.  I simply slide the metal rod of the handle the foam brush, drag it along the lip of the glass jar as I take it out to remove some excess, and start rolling.  Its easy to always dip it back in.  I do roll quite a bit, but it is only to put on a thin initial coat.  This is of course the coat that soaks up like crazy so I'm always dipping back into the jar, but as I get to the end, i want to make sure I don't have too much left on the brush so that there isn't too much excess on the print.  The beauty of my jar is that once I'm done, I just pop the foam roller brush off the rod and put the lid on.  It stays dry and always ready for the next coat.  I do clean the brush if I was to make another batch, but there really hasn't been any issue with the foam living in the jar as long as its air tight.

Now what I do next is not in the video, but it certainly helped me immensely.  I use a dry roller to run over the entire print, over and over again, until all of the bubble have pretty much been worked into the print.  I don't push hard, but the action just breaks up the bubbles before they  can dry as a bubble.  I of course put this roller into a jar too to not dry out in between the coatings and when I done for the day, I will wash it in warm water and let it dry for the next time.  Since I've been doing it like this, I haven't had any issues.  Sometimes I do get scared when I see the print and can't work it anymore, but after I come back 20 minutes later, its perfect.

Looking at your sample picture makes me think you have actual dry chunks.  Someone else suggest straining which is what I will start doing as well because I can see them in the bottom of the jar.  I have always wanted to take some pics of my technique and post it so that others can learn from my many many experiments and steep learning curve.  Maybe I'll get around to it soon!

Kiran
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