WetCanvas
Home Member Services Content Areas Tools Info Center WC Partners Shop Help
Channels:
Search for:
in:

Welcome to the WetCanvas forums. You are currently viewing our boards as a guest which gives you limited access to view most discussions, articles and access our other FREE features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload your own photos and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please visit our help center.

Go Back   WetCanvas > Explore Media > Acrylics
User Name
Password
Register Mark Forums Read

Salute to our Partners
WC! Sponsors

Our Sponsors
Reply  
 
Thread Tools Display Modes
  #1   Report Bad Post  
Old 12-07-2017, 02:50 PM
Dorice's Avatar
Dorice Dorice is offline
Enthusiast
East Coast - New Brunswick, Canada
 
Join Date: Jan 2005
Posts: 1,491
 
Hails from Canada
Gesso?

Hello,

I am new to acrylics. Wondering if everyone does a treatment of gesso on canvas prior to beginning, or is this necessary at all? Thanks!
__________________
Dorice
If your knees aren't green by the end of the day then you ought to seriously reexamine your life.
-Edith Wharton

http://dorisdaigle.ca
http://doricewatercolours.blogspot.com
Reply With Quote
  #2   Report Bad Post  
Old 12-07-2017, 03:00 PM
bvanevery's Avatar
bvanevery bvanevery is offline
Lord of the Arts
Asheville NC
 
Join Date: Dec 2012
Posts: 2,692
 
Hails from United States
Re: Gesso?

You may not paint on raw canvas with no gesso, unless you want your work to rot away as the years go by. You could seal it with something transparent, but you must seal it somehow. GOLDEN has this to say about sizing, which is done even before gessoing:
Quote:
Controlling SID in Acrylic Paints

Support Induced Discoloration (SID) is a phenomenon that occurs in acrylic paints and mediums. Many common artist supports have impurities that can discolor a translucent acrylic gel layer or color glaze, and a size must be applied before gessoing to ensure the products stay clear as the films dry.

As a paint film cures, the water exits two ways: through the surface of the paint and through the back of the support, if porous enough. Canvas, linen, wood and masonite are all porous enough to allow water to absorb into them. During this drying process, the water is actually in equilibrium moving back and forth between the acrylic paint and the support. The water extracts water-soluble impurities such as dirt, sap, starches, etc., from the support and deposits them into the acrylic film. The result is a discolored (typically amber) film, with the degree of discoloration dependent on the amount of contaminants deposited and the inherent level of impurities in the support.

SID contamination often goes undetected. In most cases, the paints applied contain a sufficient level of pigment, thus a strong enough color, to conceal the yellowing. However, in a transparent glaze and especially in thick translucent gel layers, SID becomes quite noticeable. SID can transform the appearance of an Ultramarine Blue glaze into a lower chroma, greenish color. Gesso alone will not stop SID, and different gels and mediums have varying degrees of blocking capabilities. The best product Golden Artist Colors produces to prevent SID is GAC 100. This thin medium works best when 2 or more coats are applied directly into the support. Once dry, the canvas can then be primed and subsequently painted with less potential for discoloration. Pre-primed canvases can be sealed with GAC 100 as well. Apply one or two coats onto the surface, and follow with at least one coat of gesso to regain tooth if needed.

A lot of people buy preprimed and prestretched canvases, so they don't have to do the labor. Not all preprimed coatings are created equal, from an archival standpoint. They can contain "bad stuff" that will ruin your work, and you won't know what's in that preprimed surface unless your product manufacturer chooses to disclose it. And you choose to read / understand it, which may be a nontrivial exercise. If you are just beginning to paint, this is likely not much of a concern to you. Keep in mind that at some point, if you stick with it, you may care about the longevity of your work.

And speaking for myself, I care about the longevity of the 1st crude acrylic painting I did when I was 10 years old. Not that I can do much about it now; what's done is done.

Last edited by bvanevery : 12-07-2017 at 03:42 PM.
Reply With Quote
  #3   Report Bad Post  
Old 12-07-2017, 03:24 PM
Charlie's Mum's Avatar
Charlie's Mum Charlie's Mum is offline
Moderator
North East England.
 
Join Date: Oct 2003
Posts: 54,393
 
Hails from England
Re: Gesso?

You may like to gesso pre-primed canvases to make the surface the way you want it for a particular work/style. Gesso and sanding between coats can make a lovely smooth surface for, say, a floral work ...... adding other substances like marble dust or polyfiller can give a rougher finish for more tactile work.
__________________
Cheers, Maureen

Forum projects: Plant Parade projects in Florals/Botanicals, Weekend Drawing Events in the All Media Arts Events forum. Different Strokes in the Acrylics Forum.
**Information Kiosk~Acrylics**
**Reference Image Library**
**My SAA website**
Reply With Quote
  #4   Report Bad Post  
Old 12-07-2017, 04:37 PM
Lady Carol's Avatar
Lady Carol Lady Carol is offline
Moderator
Horses make me happy
 
Join Date: Aug 2002
Posts: 25,160
 
Hails from Australia
Re: Gesso?

Most of us here add a couple of additional gesso layers to pre-primed canvases. Me, more because I like to get rid of some of the tooth of the canvas and also because it helps to reduce the amount of paint that is sucked into the store bought canvas.
__________________
Carol
"Mercifully free of the ravages of intelligence" - Time Bandits
Moderator: Acrylic Forum
My websites: Discoveries With Colour Adventures in Photography
Reply With Quote
  #5   Report Bad Post  
Old 12-07-2017, 04:53 PM
~JMW~'s Avatar
~JMW~ ~JMW~ is offline
A WetCanvas! Patron Saint
Oregon
 
Join Date: Oct 2004
Posts: 3,056
 
Hails from United States
Re: Gesso?

Raw or pre primed?
Raw yes..
Preprimed - yes, if is cheaper / coarse textured
it will help with smoother paint application , or you can do an under painting layer then build to your final painting & details.
If you start to paint and get a lot of skips & spotting, (may not show up until the layer dries) that tells you it needs a layer to smooth it more..
__________________
JMW's Paintings
Improve your landscapes- http://www.wetcanvas.com/forums/forumdisplay.php?f=522
Composition Tips http://www.wetcanvas.com/Articles/Jo...120/index.html
Reply With Quote
  #6   Report Bad Post  
Old 12-07-2017, 06:57 PM
cliff.kachinske's Avatar
cliff.kachinske cliff.kachinske is online now
WC! Guide
 
Join Date: Dec 2014
Posts: 5,494
 
Hails from United States
Re: Gesso?

To be clear, acrylic paint will not damage raw canvas. Canvas will deteriorate over time, of course, but with reasonable care a painting on canvas will last long enough to satisfy most of us. Varnishing is a good idea as it protects the paint surface from air borne dust and other contaminants.

Surface Induced Discoloration is a real thing, but probably not something you need to worry about. As Golden points out, most paints layers will have enough pigment that you would never see any discoloration. In addition, thin paint layers that dry quickly will not have SID. It takes time for the contaminants to migrate into the paint layer.

Painting thin washes on raw canvas can give effects that you can't get any other way; which is not to say they are necessarily desirable...
__________________
A painting is never really done as long as I can get my hands on it.
Reply With Quote
  #7   Report Bad Post  
Old 12-07-2017, 08:00 PM
bvanevery's Avatar
bvanevery bvanevery is offline
Lord of the Arts
Asheville NC
 
Join Date: Dec 2012
Posts: 2,692
 
Hails from United States
Re: Gesso?

Quote:
Originally Posted by cliff.kachinske
To be clear, acrylic paint will not damage raw canvas.

That may be debatable as acrylics do contain surfactants, the migration of which can do interesting things to your painting itself. So why not also canvas? May not be as bad as with oils, who really have problems with their stuff burning the canvas, and most definitely have requierd procedures to prevent it. But I'd like to see a cite before signing off on the proposition, that canvas is immune to damage from acrylic paint.

In any event, the canvas itself needs protection from all kinds of other phenomena typically associated with making and displaying a painting. Basically, there are reasons why people have done these historical labor intensive steps, of sizing and then gessoing.

Search terms "raw canvas conservation" yields Paintings Conservation Wiki, section Raw Canvas. Issues with preserving the work of the Color Field painters, who often used raw canvas, are called out:

Quote:
Raw canvas paintings have proven vulnerable to condition issues less common or problematic in traditionally primed and painted canvases. Cotton fabric is subject to darkening through natural degradation. Contact with acidic materials, such as those found in a wooden stretcher, can cause rapid oxidation of the cotton fibers resulting in permanent discoloration—a condition known as ‘stretcher burn'. Areas of exposed canvas are absorbent and especially susceptible to staining from contaminants such as oily fingerprints, liquids, food and drink, nicotine, and other foreign matter. Grime, dust, and airborne pollutants settling on the surface can become embedded in the fibers. Mold growth directly on canvas fibers is frequently observed in higher humidity environments and may result in permanent disfigurement. Tears or punctures are highly visible on these types of paintings due to the expansive solid fields and repetitive textural weave pattern. Additionally, these canvases are often subject to later coating with non-original materials.

Last edited by bvanevery : 12-07-2017 at 08:41 PM.
Reply With Quote
  #8   Report Bad Post  
Old 12-08-2017, 09:46 AM
kin3 kin3 is offline
Senior Member
 
Join Date: Jun 2014
Posts: 440
 
Re: Gesso?

I use Gesso for white paint. I'm not a pro but Jerry Yarnell uses it and I learned a lot for him.
Reply With Quote
  #9   Report Bad Post  
Old 12-08-2017, 10:12 AM
LavenderFrost's Avatar
LavenderFrost LavenderFrost is offline
A WC! Legend
Manitoba, Canada
 
Join Date: Apr 2007
Posts: 19,465
 
Hails from Canada
Re: Gesso?

I do too, kin. And I often start a painting with a layer of gesso tinted with paint.
__________________
C&C always welcome. Michelle

mkmcreations.com
Every painting is a new adventure.
Reply With Quote
  #10   Report Bad Post  
Old 12-08-2017, 10:19 AM
Use Her Name's Avatar
Use Her Name Use Her Name is offline
A WetCanvas! Patron Saint
The Land of Enchantment
 
Join Date: Feb 2006
Posts: 3,318
 
Hails from United States
Re: Gesso?

If you buy pre-gessoed canvases (many new painters do this), you do not need gesso. You do need gesso if you stretch your own raw canvas, or paint on paper with oil (this depends).

Some people re-gesso pre-gessoed canvas if they want to tone the canvas (not start white). For instance if you are painting a forest or field you can gesso the canvas green or brown. Many people start with black canvases.

To tone gesso, just get some in a cup or container, and add a bit of acrylic, pigment, or watercolor to the gesso. You can also do underpaintings using toned gesso to save on paints.
Reply With Quote
  #11   Report Bad Post  
Old 12-08-2017, 10:21 AM
bvanevery's Avatar
bvanevery bvanevery is offline
Lord of the Arts
Asheville NC
 
Join Date: Dec 2012
Posts: 2,692
 
Hails from United States
Re: Gesso?

Quote:
Originally Posted by kin3
I use Gesso for white paint.

I'm trying to find out of the conservationists have anything to say about that. My fear would be if the gesso dries stiffer than typical acrylic paint. That could create variable stiffness in the surface of your painting, depending on where you were using more, less, or no gesso. Which I believe would be a cracking or delamination risk.
Reply With Quote
  #12   Report Bad Post  
Old 12-08-2017, 10:30 AM
Use Her Name's Avatar
Use Her Name Use Her Name is offline
A WetCanvas! Patron Saint
The Land of Enchantment
 
Join Date: Feb 2006
Posts: 3,318
 
Hails from United States
Re: Gesso?

Quote:
Originally Posted by bvanevery
I'm trying to find out of the conservationists have anything to say about that. My fear would be if the gesso dries stiffer than typical acrylic paint. That could create variable stiffness in the surface of your painting, depending on where you were using more, less, or no gesso. Which I believe would be a cracking or delamination risk.

It depends on how the gesso is made. Traditional gesso is made with rabbit skin glue, chalk, and pigment. So it will be a bit more brittle.

Acrylic gesso is basically made with acrylic polymer medium, and chalk (calcium carbonate) and is actually just house paint.

While acrylic paints are basically made of acrylic polymer medium and pigments without the chalk, so the colors come through clearly.

You can paint with gesso, but the white in it will make all your colors "pastel" or cut it down with white.

It is the water in the mixture that shrinks (stretches) the canvas. When you stretch with acrylics, you begin with a piece of canvas that has been stretched tightly over a frame and stapled or nailed on. Then you add a diluted gesso (I was taught to use warm water). This is in place of the rabbit hide glue that would have been traditionally used at this time. This, you let dry. Then you add several (up to 5) passes with undiluted gesso. By that time, the canvas is already "stretched" and you are only creating a tough painting surface (called the ground).

Last edited by Use Her Name : 12-08-2017 at 10:35 AM.
Reply With Quote
  #13   Report Bad Post  
Old 12-08-2017, 12:08 PM
bvanevery's Avatar
bvanevery bvanevery is offline
Lord of the Arts
Asheville NC
 
Join Date: Dec 2012
Posts: 2,692
 
Hails from United States
Re: Gesso?

Quote:
Originally Posted by Use Her Name
Acrylic gesso is basically made with acrylic polymer medium, and chalk (calcium carbonate) and is actually just house paint.

One thing I've learned from my conservation readings is there's no such thing as "just" you-name-it-kind-of-paint. Paints are not all created equal, they can have very different things in them, depending on who manufactures them. Conservationists have noticed that some Acrylic Dispersion Grounds ("gessos") can cause problems for works, because the cheaper products can have "bad stuff" in them. As usual, for starting information on this issue, look at MITRA's paper Grounds and Primers. I would be skeptical of anyone who thinks "house paint" is just fine for artist work; in fact this is covered in MITRA's Myths, FAQs, and Common Misconceptions.

Quote:
13) If it is a product made for the outdoors and for industrial purposes it must be long-lasting and it is appropriate for fine art purposes…

Industrial materials made to withstand outdoor (and even indoor) conditions were formulated for very different purposes than traditional art materials. There are many choices that paint manufacturers make that affect the outcome of a given product and paints produced on an industrial scale often use additives that are relatively economical and/or are the easiest to incorporate into the paint formulations. These additives can aid in creating a more workable paint and helps the paint film to withstand severe weather conditions and extreme exposure to light; however, these additives (i.e. antifungal agents, wetting agents, rheology modifiers, dispersants, anti-freezing agents, driers, thickeners, de-foamers, small additions of toxic solvents, etc.) can potentially lead to problematic consequences when these paints are used to create fine art that is intended to last for decades and centuries rather than a short time in a very hostile environment (i.e. 7-15 years). Some of these additives are known to eventually migrate out of these commercial paints after a certain period of time, industrial products are not recommended as suitable materials for grounds, paint layers, and/or varnish coatings. Additional research is required to assess whether these additives can form potentially deleterious complexes with pigments, create a hazy film on the paint surface, impart brittleness, and/or create a paint film that is more sensitive to solvents. As little is presently known about how these materials will age over extended periods of time, industrial products are not recommended for use. If artists choose to use such products, they are encouraged to record the brand, material, and date of purchase (commercial manufacturers may change their formulation often without notifying the consumer) of the product on the back of the artwork.


As for prep,

Quote:
Originally Posted by Use Her Name
By that time, the canvas is already "stretched" and you are only creating a tough painting surface (called the ground).
sizing is a step before gessoing, per articles quoted earlier in the thread. Gesso alone will not stop SID.
Reply With Quote
  #14   Report Bad Post  
Old 12-08-2017, 12:44 PM
Gsell Gsell is offline
New Member
 
Join Date: Jun 2013
Posts: 48
 
Re: Gesso?

I purchase my Canvas from Hobby Lobby. So are they considered pre-gessoed treated or am I as the artist suppose to treat that exact same canva with Gesso?

I purchase the "Classic Collection"
Reply With Quote
  #15   Report Bad Post  
Old 12-08-2017, 05:30 PM
bvanevery's Avatar
bvanevery bvanevery is offline
Lord of the Arts
Asheville NC
 
Join Date: Dec 2012
Posts: 2,692
 
Hails from United States
Re: Gesso?

I haven't chased down that particular prestretched canvas. Here are the issues I would be concerned about in general.

Has the canvas been sized properly? This is a step even before gessoing. I can imagine cheap products that are not sized properly, or at all. I would not buy those.

Assuming that's ok, does the gesso have nasty stuff in it? That will ruin your work over time? This again is probably a cheap vs. more expensive / more reputable product issue. So the MITRA folks have said, in those papers I keep referencing. There's the additional problem that, most manufacturers are not going to disclose the contents of their products. Maybe some do, but I don't personally know which ones those are.

Assuming both of those are ok, does the product have enough gesso on it? I see very little point in buying a prefabricated product, if I'm going to have to add additional layers of gesso to it, for it to become satisfactory. Sure you can just put more gesso on prestretched canvases, but then why are you even buying them? Especially for larger work as these things get expensive.

Another dealbreaker I've recently realized: did they staple the sides of the canvas? Those staples rust. The rust shows through gesso, doesn't matter how many coats I put on. I'm not going to go through heroics sealing staples with some kind of primer. It's supposed to be a finished product, ready to go. Any manufacturer dumb enough to offer staples on the sides of the canvas, isn't offering a finished product in my book. I only realized this issue recently, working with some ancient bad leftover canvases I had lying around. Most of my canvases didn't happen to have side staples, so I never realized this problem before.

And finally - this is the real clincher for me - I will not be painting any more on canvas / any kind of flexible support at all. Whether prefab, or anything I would make myself. The archival issues for this stuff are terrible. It's all about the physics of stretching things, the forces involved on the paint layers over time. There's no way you can turn this physics into a superior archival surface.

Even for rigid supports, one needs to know which ones warp and which ones don't. And why.

Last edited by bvanevery : 12-08-2017 at 05:38 PM.
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 02:48 PM.


© 2014 F+W All rights reserved.