Has anyone used EXTIRA? It is an MDF-like panel product with a phenolic resin base instead of a formaldehyde base like MDF has. Therefore, it doesn’t off-gas as MDF does (no more smell while cutting it). It is also impervious to moisture changes.
This seems a better choice for jigs than MDF (or MDO) so stability is maintained as humidity changes. Hogan Hardwoods sells it for $38.12 for a 49×97 sheet of 1/2 inch and about $4 more for a 3/4 inch sheet.
Greg
Edited 5/2/2007 8:08 am ET by Cincinnati
Replies
I tend to use paper or fabric reinforced pheolic plastis for things that need to be stable.
I haven't used the product in question, but the tech specs look good. The nearest wholesaler to me is over three hundred miles. But, I am headed to the lumberyard tomorrow, and will see if they can get single sheets.
The 1-1/4-inch thickness is interesting.
Does MDF gas off that much? Over here in the EU we have standard MDF made to E-1 grade which is relatively low in formaldehyde. In any case there are health risks associated with cutting phenolic-derived products and the stuff you are talking about is 1-1/2 to 2 times the price of MDF, so, is it worth the extra?
Scrit
I can tolerate the smell, but in LA (lower Alabama) humidity changes greatly effect MDF unless it is sealed well on all faces & edges.
Although it is more expensice than MDF, I can get quite a few jigs from a $38 sheet. Phenolic is too expensive for most jigs. Maybe there is a lower grade and source I am unaware of.
Greg
Greg,
What are you sealing the MDF with to keep water vapor from permeating it?
Rob
Rob
I have sealed it with a variety of finishes that I have had available to me, including a couple of coats of laquer (sanding sealer), varnish, and in one case paint.
I have not measured the effectiveness of it, but haven't had any issues with the finish. I have had unfinished MDF swell.
Do you ask for any particular reason?
Greg
I noticed on the MSDS on this that it is capable of spontaneous combustion under certain conditions. Friendly FYI to those who may be trying it out.
Wow. Never took time to look at the MSDS.
Hey, good point.
Won't have all those extra jigs hanging off the walls cluttering the place up...
Greg,
I asked because this subject came up here awhile ago and JohnWW the shop manager for FWW mentioned something that I had never thought about. Namely, No finish seals wood or MDF from moisture vapor transfer so even finished mdf jigs will gain or lose size based on humididty. So you should be careful about using MDF jigs that require precision in case they have changed size.
Rob
That's correct.AllI can do is slow the absorption a little. I am not doing anything that critical with jigs. But I get a bit "perfectionistic" at times. My engineering background is hard to leave in the background.Thanks for the reminder about John's MDF post. I do remember reading it. I wonder if a couple of heavy voats of wax would do a better job here. I have never tried that.
Edited 5/4/2007 3:27 pm ET by Cincinnati
An excellent material for jigs is acrylic sheet. If you check with the sign shops, that do fronts for strip malls, etc. They usually generate quite a bit of scrap that they will let you have for the asking.
the spontaneous compustion only refers to MDF dust. It is too dense as a solid to combust
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