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svrart
05-31-2002, 09:16 AM
Hi,

I try to pay attention to the thick over thin principle in oils, but am sure i have missed it a few times. I always let the paintings dry for a few days between layers. My question is - How long does it take for the paintings to crack? Will i know it in a few weeks time or does it take 50 years or so. If i will see it in a few weeks time then i have nothing to worry about because none of my old (1 year) paintings have cracked. I have also read that paintings (average thickness) are completely dried in 6 months, so the 50 year thing may not be logical. Any way, i would like some info on this matter.

Tx,

Sridhar

DraigAthar
05-31-2002, 09:29 AM
As I understand it, cracks usually form over a period of many years. It's not something you'll see right away, in most cases.

Amy

Leopoldo1
05-31-2002, 10:00 AM
The single most important principle you should adhere to is the thick over thin principle, fat over lean is always safer from the standpoint of permancy. All paintings, eventually to some extent, will have cracking of some sort due to the nature of the way oils and different pigments dry. Extremely thick paint on canvas will certainly crack no matter what principles one follows. If you like to paint thick use a more rigid support. Below is a painting that cracked using a unstable combination of colors, one being burnt umber for the darks. I don't use it anymore.......L

http://www.wetcanvas.com/Community/images/31-May-2002/creeper.jpg

http://www.wetcanvas.com/Community/images/31-May-2002/cracking2.jpg

guillot
05-31-2002, 10:13 AM
Wow Leopoldo............Burnt Umber??

That's very interesting. Can you elaborate on the subject? As I am prone to using this color, I would love to know more!!!

BTW........I absolutely love the painting. What a terrible shame it cracked.

Tina

Leopoldo1
05-31-2002, 10:31 AM
Originally posted by guillot
Wow Leopoldo............Burnt Umber??

That's very interesting. Can you elaborate on the subject? As I am prone to using this color, I would love to know more!!!

BTW........I absolutely love the painting. What a terrible shame it cracked.

Tina

Burnt Umber dries extremely fast! The only info I have on this subject is Schmid's reference to Burnt Umber and Vandyke Brown as two colors to stay away from even as an underpainting (or for anything else.) Both have a nasty habit of cracking. Simple mixtures of more stable colors will easily match them.

I actually don't mind the cracking and I tell friends that this antique painting was done many, many years ago by my great, great grandfather.LOL.....L

svrart
05-31-2002, 10:44 AM
Hi Leopoldo,

Thats a beautiful painting. How old is it?

I also use burnt umber a lot. Will have to look for substitutes.

Thanks,
Sridhar

Verdaccio
05-31-2002, 12:39 PM
All oil paintings will experience some level of cracking. Normally, cracking should not show up for at least 50 years if the painting is structurally sound. If you really want to avoid cracking for the longest extent possible, then paint on a rigid surface like panels, not canvas.

Leopoldo1
05-31-2002, 02:18 PM
Originally posted by svrart
Hi Leopoldo,Thats a beautiful painting. How old is it?
I also use burnt umber a lot. Will have to look for substitutes.
Thanks,
Sridhar

Your welcome Sridhar, Painted in '91. A good substitute for BU is Transparent Oxide Red, Burnt Sienna and Ultramarine Blue.....L

Leopoldo1
05-31-2002, 02:26 PM
Originally posted by Verdaccio
If you really want to avoid cracking for the longest extent possible, then paint on a rigid surface like panels, not canvas.

.............and watch those verdaccios where one is tempted to glaze over thinnly to stay in control of their brush strokes with under pigmented oils!

guillot
05-31-2002, 05:33 PM
Thanks for the information! I must say, your great, great grandfather painted very lovely LOL !!

Like the substitutes, they work well for me. Thanks

Tina

Leopoldo1
05-31-2002, 05:55 PM
Originally posted by guillot
Thanks for the information! I must say, your great, great grandfather painted very lovely LOL !!Tina

Tina, your words are too kind! I will certainly pass this on to my closes relative of age. I found a old family picture of him.....L

http://www.wetcanvas.com/Community/images/31-May-2002/grandpa.jpg

guillot
05-31-2002, 09:02 PM
The resemblance is astounding!! If, of course, your last tinyhead was a pic of you..........:p

Thanks Leopoldo :angel:

Tina

impressionist2
06-01-2002, 08:12 AM
Leopoldo, Good information to know. I have never used Burnt umber. My blacks and basis of my paintings are thalo green and aliz. crimson mixed. I stay away from the browns altogether. For my portraits and plein air paintings, this works out fine for me.

You wrote: "I actually don't mind the cracking and I tell friends that this antique painting was done many, many years ago by my great, great grandfather.LOL.....L"

Very clever ! However, I am thinking one could incorporate it into one's repetoire, as if it's a valid "old master" kind of choice, and after the client signs the contract and gives the deposit, the artist could ask, "Now, would you like that with cracking or without?"
:D

Btw, wonderful painting.

Renee

Victor
06-01-2002, 02:16 PM
It is my understanding that you should not use oil in the underpainting because it will dry too slow. The top coats in colour will dry faster than the underpainting. The result will be that as the underpainting dry's, it moves and cracks the dry top colour coat.

Also, the more layers in a painting, the more likelyhood it is to crack.

This is information I learned and am just passing it on so you may take it or leave it.

Victor....

Einion
06-01-2002, 03:33 PM
There are two forms of cracks in oil paintings, drying cracks and ageing cracks. Drying cracks can form very swiftly, within months of completion in bad cases but this is rare. Check my post in this thread for some more basic info:

http://www.wetcanvas.com/forums/showthread.php?s=&threadid=43457&highlight=cracking

Bear in mind, for certain pigments and/or thick applications drying can mean weeks not a few days and a dry surface is no indicator that the layer is fully dry, since like most things oils dry first on the surface.

Anyone who wants to mix an alternative to Burnt Umber, a transparent red earth like Burnt Sienna plus a carbon black can be very close to some examples and will dry much more slowly. Raw Sienna plus one of the darker quinacridones with a touch of Phthalo Blue GS makes a decent dark brown too, with a moderate drying time.

Einion

Leopoldo1
06-02-2002, 12:18 AM
Originally posted by impressionist2
Very clever ! However, I am thinking one could incorporate it into one's repetoire, as if it's a valid "old master" kind of choice, and after the client signs the contract and gives the deposit, the artist could ask, "Now, would you like that with cracking or without?"
:D

Pretty funny Renee! Actually, I believe there is a product on the market, believe it or not, that can be used to promote cracking for that old look!....L