Best support option to protect against high humidity?

Mary Jane Ansell · 10-17-2006, 05:12 AM

Hi

I have a portrait commission destined for a family currently living in Burma (Myanmar). The high humidity there is causing my client and I concern regarding potential damage (warping particularly comes to mind) to the support. They will also be bringing the painting back to a country with lower humidity in a few years time so it needs to stand up to this change.

Has anyone any experience/advice in this instance? Especially regarding the best way to construct a support (I often use canvas or linen stretched onto a 5mm piece of marine ply - would bracing this across the back be sufficient?)

The painting will be relatively small - only approx 20 x 20 inches, and as I say oil on canvas or linen.

Thanks in advance.

Mary Jane

Richard Bingham · 10-17-2006, 12:52 PM

Opinions will no doubt abound. My personal bias is paintings under 3 sq. feet are best executed on panels; larger than that, on stretched fabrics.

Extreme changes in humidity (how extreme?) will be problematic in this case, regardless of what materials are employed. On the other hand, you may be overestimating the intensity of this "shock".

High-quality plywood would be my choice in this instance, regardless of how the painting ground is prepared. An oil ground on the wooden panel would be "best" in my opinion, with the panel prepped both sides. It is well to consider the fact that it is impossible to "seal" any wooden item from changes in ambient humidity, even with all surfaces coated. In fact, it is often inadvisable to attempt it.

For my part, it would be better to use plywood 1/2" to 5/8" in thickness rather than thin 5mm (about 1/4"?) stuff. Reinforcing a panel with a cradle is a task demanding a very high level of wood-working skill. The cradle bars need to be fitted very accurately where they cross and interlock, and should not be glued to the panel along their entire length, as this will inevitably "telegraph" to the surface of a thin panel face. Suitable cradles are glued to the panel edges at the tips of the bars, and "float".

A good alternative to a wooden panel with an oil ground would be 1/16" thick ABS (acrylonitrile-butadiene-styrene) sheet laminated to suitable plywood. In the event severe changes in humidity cause the plywood to fail, an ABS veneer could be re-lined with another panel quite easily.

Marcus Lim · 10-17-2006, 09:47 PM

While there are concerns of high humidity, and its effects on the painting, it's really not a major problem as long as you adhere to two things:

Getting the painting to dry adequately before shipping

Avoid storage of painting in enclosed environment before shipping

These points serve as reminder to discourage mold bacteria from growing on it, before we even ship it to the location.
However, if you're still worried about problems with humidity, you may consider talking them into sending the painting rolled up (and in vacuum pack), and your customers can have them stretched using wood that is suitable for their environment. Hope you find these tips helpful

Mary Jane Ansell · 10-19-2006, 04:38 AM

Thanks for your helpful points Richard and Marcus.

Richard, my feeling was for a thicker high quality ply panel but will also pursue ABS (I have not used it personally)

My canvas maker just suggested MDF but I'm never keen on it personally, he also reminded me how important it will be to have the painting carried in hand luggage - he having just seen a canvas of his warped horrendously in the hold on its way to Portugal recently...

The humidity can range from 20% to over 85% (which - gasp - it is currently!)

Marcus, I shall do my best to get it thoroughly dry, actually thats a bit of a worry though as that may be very hard indeed - the family are coming back to the UK at Christmas to collect it!! :-/

Mischa Milosevic · 10-19-2006, 04:51 AM

This may sound silly but, Has anyone thought of vacuum packing? Do you think that mite work?

Marcus Lim · 10-19-2006, 06:52 AM

Quote:

Originally Posted by Mary Jane Ansell

Marcus, I shall do my best to get it thoroughly dry, actually thats a bit of a worry though as that may be very hard indeed - the family are coming back to the UK at Christmas to collect it!! :-/

Hi Mary, i meant to say the painting needs to be dried with the lowest moisture level as possible, when i suggested drying adequately. What we're concerned about is the explosion of mold bacteria that may sit with the painting dormantly in the temperate region and into Asia.

It's the same idea as having yourself in an air-conditioned environment and moving into the hot summer sun immediately - you'll find yourself drenched with moisture! That's what i want to say.

Richard Bingham · 10-19-2006, 01:48 PM

Just a couple more thoughts. MDF would be the worst possible choice for panel material in my opinion, because being compounded of wood flour, glue binders of indeterminate composition, and floor-sweepings, it is neither structural nor does it resist the absorption of ambient humidity even as well as solid wood.

Vacuum packing would be a solution if the painting were never to be exposed to a climate other than the one in which it was painted. The slower the change to different ambient conditions, the better - hence, a "slow boat to China" would be theoretically better than air freight!

Curiously, ambient humiditiy does not affect the "drying" of oil paints and the varnishes and solvents normally used with it. Oxidation is the process which "dries" paint, and while high humidity may affect the rate which solvents and volatiles "off-gas" in the process, oftimes, paint will actually "cure" better in the presence of some moisture than in a bone-dry climate such as in the Arizona desert.

Finally, one of the properties of paints which has enabled such coatings to preserve wood and other materials, is the fact that the vehicles employed are innately pretty good fungicides/bactericides. A relatively fresh painting will be unlikely to "grow" stuff . . . terpenes and other volatiles would prevent that. To this end, it would be advisable to apply a coating of an oil ground to the back of any painting support. The open backside of a canvas sized with hide glue would present an ideal medium for growing "things", however!

Richard Monro · 10-20-2006, 07:02 AM

ABS panels would be a good bet. These plastic panels are dimensionally stable and fairly impervious to moisture. Do a Forum search for ABS panels and you will find that a lot of noted portrait artists use them with great success.

Paul Foxton · 10-20-2006, 07:32 AM

Hi Mary,

I've been doing a bit of hunting around myself recently on options for supports, and came across this page about Dibond which may interest you:

http://www.welshartsarchive.org.uk/a...els-burton.htm

Mary Jane Ansell · 10-23-2006, 06:20 AM

Thank you all very much. I've researched the very helpful points raised further and have to say Paul, I'm really impressed with the Dibond you mention... I've just spoken to them and they were extremely helpful despite my very small requirements.

I was sold before they explained that The Tate and many other galleries use Dibond as a support for artwork or for any number of other uses.

I eagerly await my sample!

MaryJane.