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rjmjr
02-15-2002, 01:23 PM
Hi,

I’m new to WC and oil painting and I hope you’ll patronize one of my silly questions.

Anyway, I was reading a book that suggested using acrylics for the underpainting of an oil. This intrigues me because of the rapid drying time of acrylics and I have some familiarity with them. But as a surface for glazing? Hmm …

If anyone has experience using this particular technique I would really appreciate advise, tips, and various words of wisdom.

Thanks!

Rob

vallarta
02-15-2002, 01:45 PM
Oils over acrylics are fine. It is the method of painting I prefer above all else.

When doing work in this manner you have the following choices.

1. Use one color and then prepare at least 5 and better 8 shades of the color and paint an underpainting with it....the object here is to make a value painting.....

2. Draw a value painting in charcoal or other and then spray it with acrylic spray/or medium and then paint over it with acrylic colors. You can paint over the one color underpainting this way as well...(method 1).

3. Let the acrylic dry for a day or two. I know it should be dry in minutes but if you have laid over the second color...and/or corrected errors by painting an area out and repainting with gesso or white paint....etc then you should let the area have a good dry before beginning oils so that there is no water bloom in the final rendering.

4. Paint over the acrylic with OIL GLAZES AND SCUMBLES. These are thin mixtures of paint and medium. I suggest using Liquin for the medium since it drys fast....(meaning overnite in many cases).

You continue to paint glaze over glaze (and or scumble which means you used white or opaque paint in the mix) ...waiting for the paint to dry. If you scumble....then wait about 5-10 days before you paint over that area again.

You continue painting until your done. I further suggest you use lighter colors than the final painting in the underpainting stage and then use glazes to darken and shade in the oils. That way seems to work the easiest and makes the most luminescence.

You might look at the current copy of INTERNATIONAL ARTIST where you will find a long article and demonstration of this technique.

vallarta

Wayne Gaudon
02-15-2002, 02:15 PM
.. can't see any problem at all.

A glaze is just an application of one color over another color and where it's oil over oil or oil over acrylic, you are still just applying one color over the other.

rjmjr
02-15-2002, 03:33 PM
Vallarta:

Thanks for the post. Your info on glazes and scumbles seems to reflect what I have been reading, so that is encouraging. :)

I guess my thoughts are more regarding the physical surface …
Is it best to keep the surface of the underpainting as smooth as possible? Is there any need to prime or treat the acrylic surface before applying oil?

I'll try to pick up the current copy of INTERNATIONAL ARTIST - thanks.

Rob

rjmjr
02-15-2002, 03:38 PM
Vallarta:

Thanks for the post. Your info on glazes and scumbles seems to reflect what I have been reading, so that is encouraging. :)

I guess my thoughts are more regarding the physical surface …
Is it best to keep the surface of the underpainting as smooth as possible? Is there any need to prime or treat the acrylic surface before applying oil?

I'll try to pick up the current copy of INTERNATIONAL ARTIST - thanks.

Rob

(I accidentally posted this in a new thread :confused: oops I tried to delete it but it didn't work - help)

Luis Guerreiro
02-15-2002, 06:56 PM
Originally posted by rjmjr
[B]Vallarta:

Thanks for the post. (...) Is it best to keep the surface of the underpainting as smooth as possible? Is there any need to prime or treat the acrylic surface before applying oil?
Rob
Hi Rob,
Your underpainting should be light and smooth enough, no need to build up the uderpainting, keep it smooth, simple, values in place. This principle is applicable regardless of whether you use acrylics or oils. No need to prime or treat in any other way before going over with oils.
Regards
Luis :)

vallarta
02-16-2002, 04:46 PM
No need to treat...go ahead and paint.

vallarta

paintfool
02-16-2002, 09:39 PM
Rob, this is a very good question! I've merged this thread with the other thread you had started regarding acrylic surfaces. You can use the reply button to continue this discussion, rather than the 'new thread' bottuon. Welcome to WC! :)
Cheryl

Einion
02-17-2002, 09:55 PM
There are some worries expressed about the bonding of subsequent oil layers (especially with glazes I believe) with the underlying acrylic paint; generally this relates to delamination where the oil layers have trouble bonding properly to the so-called slick surface of acrylics and there are recorded incidences of this happening in actual work so you might want to bear this in mind. This same goes for standard acrylic "gesso" too, hence why you will read many people warning against its use. I would agree with this generally, but proper preparation can offset this to a great extent.

Einion

bri
02-17-2002, 10:54 PM
Originally posted by Einion
There are some worries expressed about the bonding of subsequent oil layers (especially with glazes I believe) with the underlying acrylic paint; generally this relates to delamination where the oil layers have trouble bonding properly to the so-called slick surface of acrylics and there are recorded incidences of this happening in actual work so you might want to bear this in mind. This same goes for standard acrylic "gesso" too, hence why you will read many people warning against its use. I would agree with this generally, but proper preparation can offset this to a great extent.

Einion

...today. I sometimes aquire the paintings of others and paint on the backs of their canvases, then take the canvas off the old stretchers and restretch it. So just today I picked out a painting and realized that I could, with my thumbnail, simply flick the oil painting right off the acrylic gesso. this was a clear example of how the oil film became less flexible than the polymer one beneath it.

~bri

snakum
02-18-2002, 12:30 PM
Bri - what do you use to prep a canvas or masonite board? I have heard others mention problems with acrylic gesso but I am completely confused about (simple) alternatives. I haven't yet produced anything that warrants concern for longevity ... but just in case a miracle happens and I do so one day I'd like to better understand canvas preparation. :D

Has anyone used Gamblin Ground or Gamblin Traditional Gesso?

Minh 'Clueless' Thong

nam26b
02-18-2002, 01:21 PM
From what I've read (as much as possible) using an oil-based ground is the best way to ensure long-term paint adhesion.

Nathan

lori
02-18-2002, 01:57 PM
nathan...you are exactly right. oil based ground for oil based painting is the best way to go. using a size and ground will set up the canvas perfectly...

anyway, about acrylics as underpainting...this is actually one of the worst things you can do for a painting. its not that it can't be done, or that it hasn't been done many, many times...but acrylic paint is not designed to do this...because of its smooth surface quality and high...plastic content, for lack of a better way to say it...the oil paint adhesion is a huge problem and is only ascerbated by thicker painting styles. these two paints have completely different chemical make-up, and that is the key to this problem.

as stated earlier, it is one that will NEVER go away by changing your technique...it is just one of those things that you shouldn't do...even though you can do it.

i recommend working exclusively in one medium or the other per painting. besides, if its an oil painter that you want to be, then its just as important to learn the appropriate technique for underpainting as it is for the upper layers, and once you get it down...there really is nothing to worry about. time factors in oil paint are an illusion if you are painting correctly, these problems will fall to the weigh side through experience.

guillot
02-18-2002, 04:27 PM
I use acrylic gesso on some of my paintings. Before I lay any oils, I lightly sand the surface, this helps with adhesion. I ALWAYS SAND AFTER APPLYING THE GESSO!

I haven't had any problems with adhesion.

rjmjr
02-18-2002, 04:47 PM
Cheryl - Thanks for fixing correcting my erroneous thread. I meant to post a reply, but I must have fat-fingered it.

Einion, Bri, Snakum, & Nathan - Thanks for the insight (this thread is becoming more and more interesting)

Lori - You got right to the center of my concern. I've always thought of acrylics as plastic - and I posted here because I couldn't picture oil adhering well to a plastic surface.

bri
02-18-2002, 06:06 PM
Originally posted by snakum
Bri - what do you use to prep a canvas or masonite board? I have heard others mention problems with acrylic gesso but I am completely confused about (simple) alternatives. I haven't yet produced anything that warrants concern for longevity ... but just in case a miracle happens and I do so one day I'd like to better understand canvas preparation. :D

Has anyone used Gamblin Ground or Gamblin Traditional Gesso?

Minh 'Clueless' Thong

minh,

i have never used the gamblin stuff which you mentioned, but here's some relatively easy and rapid ways to prepare a panel or canvas.

C A N V A S
~~~~~~~~~

1...buy polyester "canvas"

2...paint

OR.............................................................................................

1...size the canvas with dilute hide or rabbitskin glue

2...let dry a day

3...paint

OR..............................................................................................

repeat #1 & #2 then use some HOLBIEN Foundation White as an oil primer. apply in one undiluted coat with 6" drywall knife if you don't want strokes, or slightly diluted with turpentine you can apply as many coats as you want. let dry two weeks (approx)

paint


P A N E L
~~~~~~~

1...sand panel

2...degrease with denatured alcohol

3...size with hide or bunny glue (let dry one day)

4...apply glue/whiting/titanium gesso. people tend to call this "traditional gesso" (see other site for recipes) tajkes a bit longer to apply, but after one day of letting it breathe-dry(lingering moisture) you can paint on it right away.

OR............................................................................................

1...sand panel

2...degrease with denatured alcohol (rid of finger prints, etc.)

3...size with regular strenth or slightly diluted hide or bunnyglue

4...let dry and paint

OR...if you want a white ground....................................................

repeat steps 1-3

4...let size dry a day and apply your HOLBIEN Foundation White to panel with brush in slightly diluted coats or if you want minimal brush lines in your ground (and this is cool...i do it all the time) apply the white oil ground with a brush without diluting it. tamp/dab the ground smooth, by making a dauber: (roll old soft t-shirt material up to soft mass about size of baseball or softball, wrap this with old bedsheet material and twist and tie with twine or linen tape...you'll hold this part) just move all about the panel (or canvas) and softly pounce out the ridges(remember, full strength paint here, ...this will result in reducing the thickness of the ground, obviously and thus the opacity, but if one coat isn't good for you, two or three should be sweet! I love the pouncing and have many pouncers of various sizes and even use small balloons or the fingers of latex gloves for ultra-fine areas if you want to pounce the full strength glaze real smooth or thin. various materials wrapped around your cotton ball/mass will give you different livliness factors~leathers, gauzes, etc.

******let me suggest a very simple, inexpensive and white surface to work on if these are still a bit too involved (which they're not really, but...): from the JERRY'S ARTARAMA catalog, get yourself some MULTIMEDIA BOARD. you may have to look a bit to locate the add---in the papers section usually. it is like a hard-core, white parchment and will retain its flatness under some extreme conditions. it will snap if you really bend it hard, but will take multiple oil layers and retain a flat demeanor and the best thin is...NO PREP!!! you can just:

1...get some

2...paint

3...smile

~bri

***okay, in editing i'll add a couple things:

1...i say Holbien foundation white because this will cut your time so you don't have to make a lead white ground.

2...concerning the Multimedia board: i usually apply some diluted veils or velatura to this before commencing. here are some ideas...brush out a thin layer of oil paint and pounce it down. let dry. brush out another veil of another color and with crumpled ball of plastic food wrap or silk dab all around making sure to change the positioning of your dabber and youll end up with crinkly faceted ice-crystal-like shapes which can be great underlying activity for a painting so you don't start with a drab monotony...nothing wrong with flat color...but experiment with this...you'll love it. works great on that Multimedia board.

guillot
02-18-2002, 10:14 PM
Sorry Bri - for some reason I thought you were asking about acrylic gesso :o , or did you ask about that in another thread?? :confused:

Well, when it comes to the gesso thing, just in case you want to know, acrylic gesso is not the same thing as acrylic paint. Gesso is porous, textured, and more absorbent than acrylic paint, and it's made that way to give a good tooth for adhesion for later applying layers. You can not use acrylic paint for gesso as a ground for oils because delamination of the layers will occur eventually. You can use acrylic paint for an underpainting if it is done properly. You have to thin it very very much. Rule is the thicker and slicker the acrylic paint, the less adhesion property.

If you do use acrylic as an underpainting, make sure that it is bone dry (moisture free) before you put any oils on it, or your in for problems.

ONE DISADVANTAGE TO OIL GROUNDS: is that if you don't apply sizing to your linen, cotton, etc., the oil will eventually damage the fibers. For this you have to apply rabbit skin glue to the canvas before painting.

It is very safe to paint with acrylic underpainting if it is done properly. There are also many different ways to "underpaint". Sometimes I underpaint in acrylics, sometimes I underpaint in oils, sometimes grisaille, there are many ways to "underpaint". You decide what best suits your needs. Many famous artists use acrylics as an underpainting and have had no problems. The trick of course is to do it "right the first time". VERY VERY THIN underpainting.

So, bon jour. I hope I did not confuse you ! Oh, and welcome to Wetcanvas!! It's a wonderful place to come to!!

;) :angel:

Tina

guillot
02-18-2002, 10:18 PM
Bri...........I'm so sorry....I'm just really messing things up tonight. Please forgive me. This above was meant for ROB...........



Tina hangs her head in shame..................SHAME!!!!

sorry!!!!

Tina

bri
02-18-2002, 11:05 PM
...for shame! chin up, now! ...everybody together now-just-a-spoonful-of-sugar-helps-the- ...whoa!...i just had the urge to graft that mary poppins(or was it julie andrews?) song seamlessly into CREAM's Spoonful and back again....forgive me, but that is a definite project for another evening!

anyway, it's okay, last year i accidentally, at another site, logged in as another member because i was addressing or quoting them and their name was on my mind...it was only one post and i posted that i goofed, ...so i know how it rolls.

the thing about acrylic gesso is that it's flexible. on a panel it's probably not a hyooj deal, but if you can get your acrylic ground white enough after sanding to your liking in as few coats as possible then stop and start painting. it's when your oil film becomes less flexible, especially if it's on a canvas, that this is most perilous. not the Ampersand product, but the old HOUSTON-ART "Gessoed Masonite" product was a sweet and cheap readily available panel primed with polymer "gesso" but the gesso layer was hard and ultra-thin as well as VERY adhered to the VERY rigid 1/8" tempered panel. smooth finish, too...a cool, blue-ish white ground. they seem to be called something different, now:MONA LISA PRODUCT and the product itself is different, too-more like the Ampersand product with more of an eggshell finish which chips off more and is a much softer ground. good for silverpoint's though!

getting to the important part, though, it's the handling/working properties/feel of oil grounds and "traditional" glue/whiting grounds that makes them superior first and foremost. you can also control the absorbency of a glue-whiting ground with a great degree of predictability.

i recommend them!

~bri

Einion
02-19-2002, 05:54 PM
The pros and cons of oil grounds vs. acrylic grounds have been and will continue to be argued ad nauseam in books and in online fora but in case it has escaped anyone's attention one ground is not suitable for all purposes. It is important to remember there is no one "oil ground". In the past there were huge variations in oil grounds (which the all-encompassing term "gesso" is now erroneously used for) so I would caution people to be precise about exactly what it is they are recommending. The primer for a panel could be very different from that used for a canvas, and applied quite a bit more thickly to boot, because, like all good craftsmen, they knew and understood the differing properties required by different supports. Even a moment's thought about this will make it plain that a "one-primer-fits-all" answer just isn't good enough.

Since nobody else mentioned it I think it's worth bringing up that rabbitskin glue is probably the weakest component of traditional ground preparations and on canvas is the source of a number of problems. Most conservation research points to neutral-pH PVA (also called PVAc) being a far superior sizing material so it's worth looking it up and seeing if you want to make the switch. It is also much easier to apply successfully.

As far as acrylic primers go, I have used a couple of brands over the years and they shared the same property when dry - they looked quite matt and had a slight "blackboard" feel (you know, when you catch your fingernail on it it makes your skin crawl?) like Tina mentions. This would be the minimum I would think suitable for oil painting on. There are a number of artists who think adding some material for additional tooth (blanc fixe, marble dust, lithopone and diatomaceous earth for example) and/or sanding the surface to leave fine scratches are important to improve the mechanical bond. For those who use pre-primed acrylic surfaces, if it looks even remotely shiny I would be very cautious about using it as-is, something I have noticed more than once on commercial canvases and canvas boards. This is why I try to be careful and say a properly-prepared acrylic primer, as problems similar to that reported by Bri are definitely possible.

Regardless of which ground you favour, take a look at your support first, is it flexible? If it is, should the primer then be flexible, considering that the oil layer will become brittle over time? These two questions are rarely considered and I'll bet most people have not thought about the second in particular, it is certainly rarely mentioned and requires research and thought.

If you paint on stretched canvas, as you know it remains flexible and hygroscopic (subject to dimensional changes with varying humidity) until it starts to break down. Since the canvas remains flexible it makes sense that the primer, which is intimately attached to it, should also remain flexible, at least partially. So, for those of you who favour an oil ground, does it become inflexible over time? If you don't know the answer to this then you shouldn't recommend it so easily. It is for canvas that I think a good acrylic priming is probably ideal.

This discussion is only relevant if you paint in a suitable manner, a good ground won't save a poorly-made painting. So if you don't worry about longevity, don't worry about this.

Einion

Einion
02-19-2002, 05:58 PM
Originally posted by bri
but if you can get your acrylic ground white enough after sanding to your liking in as few coats as possible then stop and start painting.
Why as thin as possible (especially re. acrylic primer)? Certainly this is important for traditional oil primers on flexible supports but panels could have six or seven coats of gesso.

Einion

bri
02-19-2002, 08:22 PM
...hello,



concerning rabbitskin glue: it is reliable. it is reliable as sizing and as the base for so-called "traditional" gesso. i would like to ask you:

what is difficult about rabbitskin glue to apply and how is pva "far superior"?

i "precisely" recommended holbien's product as a great oil primer for canvas or panel. could primers be different for panels and canvases?...yes. must they be different?...no.

i will never argue anything ad nauseam. i am, however a living witness, not an armchair prophet, to the fact that everyone i have ever known who has tried oil grounds in general and/or glue-pigment(such as glue/whiting/titanium) gesso has never gone back to plastic. if i were to paint an acrylic painting tomorrow, it would not be on an acrylic primer, either. the real fact is that acrylic grounds are not really absorbent and for the most part, do not resemble the gripping aspect of a chalkboard. if one sands, etc. before painting, a polymer ground, they are probably better off, but, as lori mentioned, oil paint and acrylic paint are different materials.

if a work merits it, it will be preserved.

~bri

_________________________________

eat an eel quesadilla, you risk your life

Leopoldo1
02-20-2002, 01:56 PM
Originally posted by bri
i usually apply some diluted veils or velatura to this before commencing. here are some ideas...brush out a thin layer of oil paint and pounce it down. let dry. brush out another veil of another color and with crumpled ball of plastic food wrap or silk dab all around making sure to change the positioning of your dabber and youll end up with crinkly faceted ice-crystal-like shapes which can be great underlying activity for a painting so you don't start with a drab monotony...nothing wrong with flat color...but experiment with this...you'll love it.

Bri, The Panel Man, please play that tune again! I am very interested in your pounce and crinkle saran wrap ball technique, as I know months back you posted a pic with that impasto backgound. Can you elaborate more on this and would like to see a pic where you used this! Thanks in advance! :oL

LarrySeiler
02-20-2002, 07:54 PM
I know a couple of well known wildlife artists, both of whom 20 years ago stepped out of the commercial/illustration business job world to go fulltime into their wildlife art.

Their practice is to do an acrylic underpainting and finish off with oils over the top.

For several reasons, one...yes, speed and meeting deadlines for commissions and competitions; two, oil has a perceived value among patrons and by painting a layer of oil over the top can be called an "oil" painting.

Another reasons is the richness of the oils can create the illusion of a particular area being "prettier"...for example say the colors of a woodduck's head if painted with oils will appear richer than surrounding areas by comparision.

Many artists produce a large original for the purpose of making prints from them, so they are not necessarily concerned whether or not the original lasts. In a frank discussion with one of these artists, I asked about the fact that you could take your thumbnail and scrape the paint off? His response was a shrug of the shoulder and ..."so?"

Their intent is for the print market, but don't seem to hesitate when someone wants to buy the original to sell it. Personally, I have a problem thinking the patron's investment is in something that lacks in permanence.

Larry

bri
02-20-2002, 09:26 PM
Originally posted by Leopoldo


Bri, The Panel Man, please play that tune again! I am very interested in your pounce and crinkle saran wrap ball technique, as I know months back you posted a pic with that impasto backgound. Can you elaborate more on this and would like to see a pic where you used this! Thanks in advance! :oL

okay...here we go.

somehow i always run into trouble trying to post but here goes.

fortunately i like to document some of this stuff, so folks can publicly humiliate me...:crying:

i will post three images. the first will be the crinkly-wrinkly ground so you can see what that looks like. this particular one is 8" x 8" and i called it school bus yellow on brackish green
it is, if i remember, some kind of cad yellow deep mixed with burnt sienna on a blackish or charcoalish green. here it is, just the ground:
Originally posted by Leopoldo


Bri, The Panel Man, please play that tune again! I am very interested in your pounce and crinkle saran wrap ball technique, as I know months back you posted a pic with that impasto backgound. Can you elaborate more on this and would like to see a pic where you used this! Thanks in advance! :oL

okay...here we go.

somehow i always run into trouble trying to post but here goes.

fortunately i like to document some of this stuff, so folks can publicly humiliate me...:crying:

i will post three images. the first will be the crinkly-wrinkly ground so you can see what that looks like. this particular one is 8" x 8" and i called it school bus yellow on brackish green
it is, if i remember, some kind of cad yellow deep mixed with burnt sienna on a blackish or charcoalish green. here it is, just the ground:
http://www.wetcanvas.com/Community/images/20-Feb-2002/schoolbusyellowonbrackishgreensecond.JPG

bri
02-20-2002, 09:42 PM
...now here is the second of three images...a three inch square detail of the rip-saran-crinkle veil:
http://www.wetcanvas.com/Community/images/20-Feb-2002/schoolbusyellowonbrackishgreen3inchdetailJPG.JPG

after the underveil was dry, this takes three or two minutes for an 8" x 8" panel...just brush on with a big gnarly housepainting brush then hit it with the wrinkly plastic wrap, leather, paper, interior wrapping paper(like you get with new shoes or some boxed clothing)works great). you can just keep dabbing in the same place if it is too severe and it will soften up, sometimes by way of multiplying the number of little crinkles to give a quieter feel.

bri
02-20-2002, 09:56 PM
...is only the beginnings of this painting. i have it on slide, i know aand photographs...where they are, i don't know but will post them after i dig 'em up. i WILL post them though.

here is the first stage of painting.

PASS IT AROUND
OIL
(please do not alter image~thanks)

http://www.wetcanvas.com/Community/images/20-Feb-2002/passitaround2.JPG

i will post better examples in the future, but for now, this is how i work with the active ground-veils.

hope this helps, Leopoldo...email me for more examples of grounds. i know i have a few scanned.

~bri

Leopoldo1
02-20-2002, 10:55 PM
Originally posted by bri
...hope this helps, Leopoldo...email me for more examples of grounds. i know i have a few scanned.

Really cool:cool: Bri, I like this alot! It seems this same effect could be attained in the traditional gesso recipes in the preliminaries but limits oneself where one would need a smooth transition? I noticed you left the cheeks, parts of the forehead, eyelids, lips, chin, etc smooth which allows for a very, very interesting perspective! Good going, you are not afraid to explore your already attained abilities! ;)L

bri
02-21-2002, 12:02 AM
...what you mean when you say that i "left" those parts smooth. the areas of the rip-van-crinkle veil that were more dense were just incidental during the two minutes that entail veil#2 application (20 seconds) and dabbing the plastic wrap material,(one or two minutes). then the paint was tossed on. my whole thing is being minimal with these things. if what you need is all there, then what is all the subsequent activity about. i need to get stuff on the panel- you can see that there's less than an hour of painting there, but i like the way the activity in the ground helps stimulate the eye an dhelp it fill in the rest. obviously different than a dead-flat background and i can feel comfortable looking at less and having it register as more (or at least closer to where i want to be).

if, in fact, i am working with a two veil system, my first color is applied and forgotten about. i'll toss them aside and then i'm real happy two weeks later when i discover them...a la "wow...i forgot about these!" then when i do the second veil with chris crinkle, i can put them aside then, or paint on one that is wet, provided i can keep my fingers out of where they don't belong...which has always been a problem for me...

not for everybody or everything, but i like to dance through these, and not piddle around...i've done enough of that and time is hurling on down to the big fire, so i like the way these are going. in fact, this thread has got me all jazzed up about it and no one here to paint :( thanks all!!!

Leopoldo, if you remember my silverpoints, i am only doing that in oil. i like the stuff which is representational but expressionist to the point of a manditory direction away from reality...ESPECIALLY when there is a bunch of stuff left out but the result says worlds more! look at a camille claudel how stuff seems illuminated to the point of being seared or eroded away by the light. yeah...that is it! WHAT THE *%@#...i am wasting my time sitting in front of a computer!!

gotta go.

~bri

Einion
02-23-2002, 01:34 AM
Originally posted by bri
i will never argue anything ad nauseam.
Hiya. I didn't mean you, I meant in general.

concerning rabbitskin glue: it is reliable. it is reliable as sizing and as the base for so-called "traditional" gesso. i would like to ask you:
what is difficult about rabbitskin glue to apply and how is pva "far superior"?
Glutoline glues, to include the whole class now almost solely represented by rabbitskin glue, are a major source of poor ageing performance in oil paintings; don't believe me, look it up the conservation research yourself. BTW in case you were not aware, many grounds used in the past were based on other members of this class, including fish glues, which show superior performance in almost all respects to bunny glue.

Speaking of its use as a size, what is tricky about applying it? Correct me if I'm wrong but you have to apply it warm for a start, and there is a fairly narrow band of temperature in which it should be used? Same goes for the consistency, which alters during use due to evaporation of water. If I recall correctly, if the consistency is too thin it penetrates the canvas too much and leaves too thin a layer on the surface, if too thick and it does not bond properly. If it is applied too thinly it does not sufficiently isolate the canvas from the ground (obviously much more of a problem with an oil ground) and if applied too thickly the ground does not sufficiently bond to the support, mechanically.

If used as a binder in a ground the same temperature range applies. If the glue is too strong (i.e. thick) the ground will put stresses on the canvas and paint film. Too weak and the filler can chalk and/or flake off (poor adhesion and cohesion) plus its high absorption can weaken the bonding of the overlying paint film (to itself and the ground). Plus in the past there could be a number of supplementary additives like honey (which improves adhesion and elasticity) which again are rarely if ever used or recommended today. The gesso ground, dredging my memory, was developed for tempera painting long before oils were used by artists and here its shortcomings were and are much less of a problem - rigid supports, flexible paint film. And as I read once, if gesso was so good for oil painting why did someone feel the need to develop an oil ground? :)

Sure sounds tricky in my book!

Recent research suggest that neutral-pH PVA is far superior because it is much less hygroscopic and hence it does not promote cracking, microorganisms don't like to munch on it and as an added bonus it ain't stinky! :D

could primers be different for panels and canvases?...yes. must they be different?...no.
They should be different - the two supports place entirely different demands on a primer during the life of a painting, hence the primer should be tailored to suit. True gesso is fairly inflexible so is better suited to rigid supports.

the real fact is that acrylic grounds are not really absorbent and for the most part, do not resemble the gripping aspect of a chalkboard.
They can be indistinguishable if you get the proportion of binder to filler correct.

everyone i have ever known who has tried oil grounds in general and/or glue-pigment(such as glue/whiting/titanium) gesso has never gone back to plastic.
Fair enough, each to his/her own. But on the other hand there are great number of painters (including some of the most respected names in contemporary painting) who have gone the opposite way, discarding traditional grounds in favour of PVAc and acrylic primers both for ease of use and for superior long-term performance. Since many of them do their own tests and/or read ongoing research in the matter I think this is worth more than just a passing thought.

By the way you didn't answer my question, why as few coats as possible?

Einion

rjmjr
02-26-2002, 04:17 PM
Tina, Bri, and Enion,

Thank you so much for taking the time to respond in detail to these posts. I think I know which grounds / primers I'm going to try - I guess I'll post back every 20 years with a delamination update…

- Rob