station mold material that wont warp?

[BradRob]

Here is a question that has probably been answered before at some time.
I am looking for station mold material that wont warp. On my first build i used 1/2 inch plywood . After cutting out the molds they sat flat for a while but i noticed when installing them on the strong back that they warped. Most of them i was able to straighten by adding 1 by material to the backs to stiffen and straighten them. Others just would not un warp so i used 1/2 inch OSB ply and had no problems. I was looking at the old molds for my prospector the other day and every single mold was warped after sitting around for a year. I was wondering about MDF, will this material warp? I also have thought about laminating 2 pieces of 1/2 inch osb or plywood together to resolve the issue but i realy want 1/2 inch stock for the molds. Will all material warp over time? I need to make a desicion soon. I dont want to cut out the molds to soon if they are just going to warp before i have a chance to get them installed and trued on to the strongback. Any thoughts or sugesstions? MDF is about 18 bucks a sheet and OSB is only 7 bucks. I dont mind paying the extra cash but not if they will warp. I will just use the osb. set them up quickly as possible and then think about them as being disposable when the pojects are done.

[Jeff in Farmington, MI]

I know that there are many different opinions on this, but I can say that I have used both 1/2" MDF and 1/2" OSB without issue. I intentionally avoided using a common grade of plywood because it tends to warp.

Both MDF and OSB have worked very well for my purpose, especially because I have not used staples during construction. Staples would certainly hold better in plywood than in MDF or OSB, and if I were using staples I might consider paying the extra cost for a quality hardwood plywood. Sealing or painting the MDF or OSB to protect again humidity should not be necessary. I have not seen any moisture related damage to these materials unless they actually get wet.

Jeff

[Adamv]

I've used 1/2" MDF and really liked it. I cut the forms and let them sit for about 10 months (in a dry place), and they didn't warp at all. In theory, MDF shouldn't warp at all (as long as it is kept dry) because it is perfectly homogenous throughout. I also like MDF because it takes a pencil line nicely and is relatively easy to work. I built stapleless, so I can't comment on it's ability to take staples.