Fello Knots Folks,
I have been making my own stretcher frames for inkjet canvas prints that I produce. I have been building the frames out of douglas fir that has been in my dry basement shop for a month or so, with moisture content around 11%. I am starting with kiln dried douglas fir studs. The frames have been shrinking with the dry heating season here in Connecticut, causing the canvas prints to sag. Many of the prints are 30″x40″ final size or larger.
I know that wood shrinks with the seasons, but am wondering if there is a hardwood that would be a better choice for these frames. I am looking for something that doesn’t shrink much, but also doesn’t cost a fortune.
Does anyone have a suggestion?
Thanks,
John
Replies
Use furniture grade kiln dried wood...
Edited 2/13/2009 11:42 am ET by RickL
Using 1/4 sawn fir will help. I did a bunch of stretchers a couple years ago and was able to get some material from my friendly local lumber yard. The material they sell for mill work works well and they sometimes have short pieces in their "$2 and $4 a board bin".
You may already know this but an easy cure for the "sags" is a light misting of water on the back side of the canvas. This will shrink the canvas and tighten it up. Go easy on the mist; I have experienced shrinkage so dramatic that it pulled the canvas right off the stretcher! If it's not quite enough the first time, just repeat.
Best Regards,
Mack
"Close enough for government work=measured with a micrometer, marked with chalk and cut with an axe"
"Using 1/4 sawn fir will help." known in building/lumber stores as "vertical grain" -- fun thread about this recently.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Edited 2/12/2009 11:59 am by forestgirl
I build non adjustable stretchers(i.e.no wedges to readjust the canvas) for a well known artist and up to 40"by40" use k-d poplar and bigger up to 12' by 18' folding even a triptic (sp?) using 3/4" poplar plywood .I use 1/4 ply gussets to reinforce it.
Don't confuse KD framing lumber with KD cabinet grade lumber. They are not dried to the same moisture level. You should be looking for lumber in the 7-8% range. The wider you make the frame parts, the more they will move.
Beat it to fit / Paint it to match
inkjet canvas prints ..
No artist but I have worked on a few very large format inkjet printers. Never worked on one this large but I once saw one at a printing show (here in Chicago) that looked like it was printing a 12 X 15 foot rug!
Not sure this will sound the way intended but are you sure it is the frames and not the canvas expanding and contracting? Just a thought. In my humble opinion it 'breathes' just like wood does. You may fight this forever unless the canvas is stretched very tightly.
I 'think' I have seen Vinyl do the same thing and has nothing to do with the frames.
OK, so the frames and materials both move. Maybe a center horizontal and vertical stretcher would help? As in a frame with centered '+' .
Edited 2/13/2009 6:56 am by WillGeorge
How wide are the frame members and how are you making the corners? I'm also inclined, as someone else already suggested, to think that the problem is with the canvas or your stretching and attaching technique, not with the frame's moving since a frame doesn't shrink very much. I make large stretchers for my wife's oil paintings all of the time and we haven't had problems in New England.
John White
Former Expert and retired FWW Shop Manager
I'm thinking that this is not truly a wood shrinkage issue.
Assuming that the frames are made from boards that are a couple of inches wide, the amount of shrinkage that you'd be experiencing would be VERY small -- probably a few thousands of an inch.
And wood does not shrink along its length (at least not significantly).
It's more likely that the stretched canvas is causing the boards to bend or twist just enough that the canvas sags in some spots.
I, too, think your problem is with the canvas.
My father's business made a lot of silk- screened posters, and his production man used only lumber yard 1 x 2 pine for the frames (with corrugated fasteners in the corners!). They kept the screened frames for years in case they had a repeat order, and the screens, which were stapled to the frames, were always as tight as a snare drum.
kreuzie
I agree it's a canvas problem, not a wood problem. I used to build stretcher bar frames from doug fir for a living.
If your canvas is too thin, likely for a digital printer, it will need to be stretched tighter or thicker canvas should be used.
Expert since 10 am.
John,
Lots of good advice since 2-12! I don't know what your level of experience is with making these stretchers so don't be insulted if I suggest something that is obvious to you.
1. How are you stretching the canvas? If you're just pulling it by hand and stapling, it's not tight enough. There is a special tool for the purpose available from art stores and the like. It looks similar to a tool used in the sheet metal trade for bending small pieces. It grips the canvas and you roll the tool over the stretcher using it as a lever to tighten the canvas.
2. Are your stretchers rectangular in cross section? If they are, you can improve their performance by beveling the face. The canvas should not even contact the front face of the stretcher. I use a bevel of between 2 and 5 degrees depending on the width of the stretcher.
3. I agree with the poster that suggested the "T" brace in the middle of a large stretcher.
Best of luck and please post you results!
Regards,
Mack
"Close enough for government work=measured with a micrometer, marked with chalk and cut with an axe"
Hi Gang,
I appreciate all of the advice. The more that I research this process, the more that I realize it is the canvas that is contracting and expanding. The manufacturer of the canvas confirms that this is the case.
I may need to make keyable stretchers that can be tapped into a state of further tightness. I have taken the advice to use furniture grade kiln dried poplar instead of kiln dried fir. Does anyone have any ideas how to make my frames keyable? I have been glueing up the mitered corners, and even adding Dominos to the larger ones. I have been adding in cross members on larger frames also. the stretchers are 1.25 inches deep, and are 1.75 inches across.Thanks,John
I always used #10 cotton duck canvas, almost bulletproof. You should need nothing fancier than corner bracing(rabbetted is best) on smaller frames;half-lap cross braces on large ones, and you're good to go. As mentioned, a welder's vise grip with wide flanges helps to really bear down tight when you stretch the canvas.
best,
jpExpert since 10 am.
Edited 3/6/2009 6:50 pm ET by jackplane
I would not go to great lengths to complicate your stretchers. I've done many large ones (the size you're making and larger) with simple miter joints. The really big ones get corner braces and/or mid span supports just glued and nailed (pneumatic gun).
Putting the canvas on TIGHT and EVEN is the key. If you don't already have a tool that is suitable--invest! They are not that expensive (less than $25) and will make the job EXPONENTIALLY easier! The tool that is designed for this job grips the canvas and a rounded portion of the tool is rolled over the stretcher giving dramatic leverage. With this tool it's easy to bow the stretcher so be careful and patient.
If a canvas should loosen up the, water mist trick really works--honest! I had to do several before I got the hang of getting the canvas on correctly. The beveled face is another trick I learned after many stretchers. The slight bevel is a bit of a pain to keep track of while cutting and assembling but it really helps give a professional result.
Best of luck!
Mack"Close enough for government work=measured with a micrometer, marked with chalk and cut with an axe"
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