French Lines and Washes with Spacers?

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Kirstie

Kirstie

PFG, Picture Framing God
Joined
Jan 16, 2007
Posts
8,395
Loc
Berkeley, CA
We usually use spacers with French mats and glass to protect the mat from possible condensation. Or we use acrylic glazing instead.
I prefer some pressure on the mat from the glass so we often use acrylic instead.

Thoughts?
 
I guess I wonder if condensation really is an issue that happens that often. I can see condensation chances going up if you live in Oregon or hang the piece in a bathroom with a shower used daily...but I have never seen a case of condensation in a frame package. Mind you, I am in Colorado where average humidity is very low, so maybe it is a larger issue in more humid areas.

I too like the look of mats under glass and usually don't do spacers with my french lines and panels. I have a piece in my house for about 8 years with no issues, and have seen pieces come into my shop from as early as the late 1800s - again with no signs that the mat touching the glass caused any issues.

As always, YMMV...
 
This is a mat embellishment and not the artwork. I don't think there is enough humidity that would harm the lines that would not also harm the mat if there wasn't embellishments on the mat.
 
What Dave said.

Wouldn't leaving a gap actually encourage condensation?

I've done 100s of lined mats and never had cause to space off the glass. The glass serves to keep the mat flat in any case. Without the glass pressing on it, it would no doubt curl up around the window and you would start to get unsightly gaps.
 
RoboFramer said:
I lerve French mats and I sometimes do space some from the glass, just a tiny bit, thinnest econospace; those would be the ones with gold leaf or foil.
Click to expand...

I have not used spacers and I have never had a problem, but again Colorado is dry.

But I have done a few with gold leaf as the panel and never thought about using a spacer for these. Based on your post, I will consider using a very thin one in the future for gold or metal leaf.

Good Idea. Thanks
 
I agree with Dave and Peter. I don't like the idea of spacers with a mat for the structural reasons Peter mentioned. We don't exactly live in the Amazon rainforest, although it can get pretty humid here in the summer. I have never seen a French-decorated mat that had any kind of apparent condensation damage. I really wouldn't worry about it. The only time I space away from the mat is when it has a slick surface like the faux leathers, and then I make my own by applying atg to a strip of matboard and slitting it to desired width, so that the rise is just enough to avoid contact.
:cool: Rick
 
I sometimes use painted mats or liners or combination of both. Heavy paint (as opposed to the slight suggestion of a French mat line) needs a slight space away from glass or you get weird optical effects where there is contact. But typically, this type of mat is usually thicker and will stay flat of it's own accord without the support of the glass.

If there is condensation, French lines or not, it's going to spoil the mat. We've all seen old frames with tide marks on the matting. :icon9: A lot of this is not condensation in the frame but on the outside of the glass which runs down into the rabbet and wicks up the matboard. Taping the sandwich inside the frame goes a ways to prevent this.
 
I have seen condensation in process just once. We had a print that had little value in an improper place in the house. The frame hung on a wall that was passed by the sun for a half hour or so every day. The print was matted. Every sunny day there was visible condensation inside the glass. Then, later in the day it seemed to evaporate inside the frame. The mat saved the print, and I saw no damage to the mat when we eventually removed the frame from the wall. It certainly was a dramatic example of why one should mat artwork.

The wall was not on an outside wall, and interestingly, the outside wall at a right angle nearby that also had frames hanging on it. Those frames showed no visible effects from temperature changes, but then the prints were not in the path of the sun.
 
prospero said:
Wouldn't leaving a gap actually encourage condensation?
Click to expand...
We can't encourage or discourage condensation. When the conditions are just right, it happens, and all we can do is accommodate it. Condensation is caused by a "dew point" condition. When humidity is present and the temperature of any surface is cooler than the surrounding air, by a certain temperature differential, condensation will form. In high humidity the temperature differential would be less than in low humidity. You can get many versions of the dew point chart online. When the temperatures of the surface and the air equalize, the condensation stops forming and begins to evaporate.

In dry climates, such as described for Colorado, dew point conditions are less likely. The same is true when indoor and outdoor temperatures are about equal. Note that condensation could form either on the inside or outside of the glass in a frame, depending on which way the temperature differential goes. The harmful dew point condition, causing condensation inside the frame, usually occurs when the frame is moved from a warm place to a cool place. It can also occur when light radiates through the glass, elevating the internal temperature higher than the surface temperature of the glass.

The dew point condition usually comes and goes quickly, perhaps lasting only a minute or less, but the resulting condensation may take hours or days to evaporate away, especially if it can soak into a porous material inside the frame. Acrylic is a better thermal insulator and it is thicker than typical framing glass, so the dew point condition is much less likely to occur on acrylic.
 
Kirstie said:
I have seen condensation in process just once. We had a print that had little value in an improper place in the house. The frame hung on a wall that was passed by the sun for a half hour or so every day. The print was matted. Every sunny day there was visible condensation inside the glass. Then, later in the day it seemed to evaporate inside the frame. The mat saved the print, and I saw no damage to the mat when we eventually removed the frame from the wall. It certainly was a dramatic example of why one should mat artwork...
Click to expand...

It would have been cool to take a time-lapse video of that happening to run in the shop as an illustration of what can happen when you don't follow the framer's advice.
:popc: Rick
 
Another Ohioan reporting in.
I do lots and lots of French Mats and I have not once installed a spacer in any of them.
So, I'll be watching here for what others have to say.
edie the frenchmatters goddess
 
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