I’ve got several projects coming up that will see daily use and it is inevitable that some of them will be from thick draftboard so I am wondering if any of you have experimented with toughing it up other than just paint?
13 Likes
I’ve never done it for anything large, but soaking it with CA glue will make it nigh-on indestructible…
9 Likes
When designing the check tray for the restaurant, draft board has proven itself impressively sturdy for the daily abuse it gets. The only exception to the all-around good characteristics is it’s propensity to soak up water. The affected spot bloats up and the once-densely packed wood fibers stay in that loosened state. If this occurs at a glued joint, that area is likely to fail.
The first solution that’d come to mind would be to use polyurethane rather than enamel (spray) paint. I recall trying a spray can of Varathane Spar Urethane and I think it did reasonably well, but it took around 3 days to completely dry to the point the surface would no longer feel tacky. I think this route is still worth pursuing, but maybe with a faster-drying brand.
5 Likes
There is a water-thin treatment for rotted wood that is painted on, called “wood hardener” I think, but the CA glue idea has to be every bit as good.
7 Likes
CA is going to be a lot more expensive and messier to work with. An epoxy paint would probably be ideal in terms of protecting the material from moisture. And if it doesn’t get wet, MDF is in fact pretty durable stuff…
4 Likes
I like this idea because I have it and it is much cheaper than CA. I’ll do a scrap and see what happens.
8 Likes
Wood hardener is acrylic suspended in a solvent, which then flashes off. It will fill voids in rotted/damaged material but doesn’t bond like, for example, a good paint or primer. The epoxy paint mentioned would be better suited.
That said, draftboard is fairly tolerant of exposure to elements. I had a weather sensor box I made hanging under an awning for well over a year, and it barely looked any different from new. Also had not “swelled” from year-round exposure to our ATL humidity.
It is, after all, wood fiber bonded with resin - i.e. epoxy.
4 Likes
With so much as a scratch that lets water in, MDF returns to a pile of sawdust it came from. By the time you soak CA glue or similar (and it would swell from that too), you might as well go to Baltic Birch as the net cost would be less.
5 Likes
You are right here, the primary reason to use thick draftboard for some small projects is that while 1/8 BB cuts great on the 
1/4" not so much so I mostly reserve it for the cnc router.
A lot of times I find inspiration at 3 am when it is not practical or polite to fire up the cnc but lighting off the is no problem.
10 Likes
Agreed - 1/8" is awesome to cut, but I find I’m repeating cuts with 1/4" as the material / glue within seems to vary so much you never know if you’ll cut through. At least draftboard is consistent.
And for small stuff, you can’t beat CA glue for hardening stuff. But agreed, that’s an expensive endeavor.
6 Likes
there are some products out there in the Wood Turning world that might work.
Look for wood stabilizers.
Pentacryl makes one I think.
also I believe they still make GIT ROT. a two part epoxy that soaks into soft wood and hardens.
when i was putting down LVP flooring in my old house I had to stabilize an area near the sliding doors at the back of the house where water had gotten in over the years.
I think it was an ELMER’s product that I came across. turned that mushy plywood into rock solid mass. 
the elmers or the pentacryl product will likely be your best bet.
4 Likes
I generally cut 1/4" more than 1/8" so I don’t see it as much problem. Looking I see 110-130 full for many quarter inch woods.
3 Likes
+1 for thin CA
3 Likes
I’ve mixed up 2-part epoxy resin and painted it on things, mostly to make them impervious to water. But it does toughen them up as well.
3 Likes
Pentacryl is a stabilizer designed to prevent green wood from warping as it ages and dries. It does not add any strength/rigidity, There are many similar products. They are often applied using a vacuum to allow deeper penetration into wood fibers.
Draftboard is already a composite of resin and fiber, you’ll be hard pressed to get anything to soak into it other than at the surface. That’s why a strong bonding product like a resin (epoxy-baed paint as mentioned several times) is the best option for surface protection - which is what I interpret your “toughen” requirement to be.
1 Like
If one is looking to stabilize sawdust, I did have a desk that was one inch thick and started falling apart after a few months. My attempts to stabilize it were constantly undermined and even the top you could see like worms under the coating had moisture making tunnels of least resistance ever-growing.
However, I found that the UV set material painted and left in the dark for a week would dissolve deeply into the wood that when left in the sun for a couple of days would harden deeper than anything that would be liquid for only a couple hours,(or seconds).
6 Likes
Great idea!
2 Likes
Try thinning polyurethane 25-50% with mineral spirits (or use a wiping poly/varnish). The first 3-5 coats will soak into the MDF, basically impregnating and hardening it. Once the MDF stops soaking up the thinned polyurethane you can start using full strength poly to build up the finish as desired, lightly sanding between coats.
I’ve never tried it, but I suppose could also try soaking your MDF/draftboard in thinned out polyurethane for a while. Once that’s cured you should be able to start applying the topcoat.
If you really want something rock hard, try soaking it in a stabilizing resin (e.g. Cactus Juice) inside a vacuum pressure vessel.
3 Likes
I use wipe on poly all the time and will definitely experiment with this.
2 Likes