contact cement question

[Mike in Mystic]

Hi everyone,

I finally got started on my workbench - an exact copy of the joiner's bench from Sam Allen's workbench book.

Anyway, things went fine up until the masonite. I used 3/4" thick MDF versus particleboard (as Allen stated in his book). I wanted the extra weight. Anyway, I mounted the Record 52 1/2 front vise without too much trouble and went ahead and prepared the contact cement and cut the masonite edge trim pieces.

I used a light nap paint roller to apply the contact cement, which was messy as hell (I'd never used it before). It went on the surfaces fine, however, so I didn't think there was anything to worry about. I went inside for about 20 minutes and came back out and checked the pieces. The masonite looked like I expected - a tacky coating, that didn't come off on your fingers. I think "great, it's time to go for it", but when I check the MDF benchtop, it looks as though I didn't put any cement on it at all. CRAP!

So, a few questions. First, I'm pretty sure my problem was using a water-based product on MDF. Honestly, I didn't even check the contact cement I used, but just from my results it seems obvious that that's the problem. So, do I need to do anything to the bench surface now in order to continue with the project? I'm considering just using regular titebond now, and some new pieces of masonite. Will this be problematic? Would it be better to try to find some organic-based contact cement and go with that?

I'm pretty annoyed at myself, as I've been strapped for shop time lately and this really brought my bench making day to a screeching halt.

Thanks for your help,

Mike

[Mo' Sawdust]

MDF needs two coats of contact cement.

[Andy Dingley]

As contact cement, I use Evostick 528 - usually sold for leatherworking. It's getting hard to find, but damn the glue sniffers, I want to use the real stuff that works !

If you've used a water based contact cement on MDF, I think the usual technique is to give it one coat, let it dry completely, then treat it as a primer and apply a second coat to do the actual gluing.

-- Die Gotterspammerung - Junkmail of the Gods

[Rob V]

I use MDF and formica all the time - use the first coat as a primer - then do a second coat. No problems.

[Mike in Mystic]

Thanks for the replies everyone. Will it matter if I wait an extended period of time before reapplying the contact cement?

I might have to wait as long as next Saturday to return to the project.

Thanks again,

Mike

[Bay Area Dave]

ah, they beat me to it! I KNEW this one, Mike! :)

2 coats: been there done the MDF lam thingy. MDF is a real "sucker".

dave

Mike > Hi everyone,

[Morgans]

Keep it covered and clean, and re-apply. No problem.

[Morgans]

MDF frequently needs 2 or 3 coats. Put more on. The can should say how long it can sit before you need to reapply to use it. In too long, put on another coat and stick it together.

I usually use a scrap of laminate, or other such thing as a squeegee to apply contact cement. Disposable, and thin coats. Thin is what you want.

-- Jim in NC

[JunkCan]

Reapply to BOTH pieces using the same type of contact cement. The new CC will reactivate the old. The MDF may even need 2 extra coats so watch for that.

[Brett B. Bonner]

I tried using the water-based contact cement once, on some formica (plywood substrate). Even with multiple coats, it didn't bond - I could pull it apart by hand. I switched to the solvent based stuff and it worked perfectly.

This was perhaps 5 years ago - maybe the manufacturers have improved the product since then, but after that experience I won't even try it.

The solvent based products do require some care to use - the vapors are explosive and unpleasant to breathe, so ventilate well and don't work near any ignition sources. I'd normally prefer the safer product but not if it doesn't work!

-Brett

[Bay Area Dave]

Yeah, I like the solvent based stuff, but work with the doors open AND wear a respirator. It sure sticks well! The fumes make me nauseous.

dave

Brett B. B> Mike >

[Charlie Self]

Nausea isn't the real problem. Too much exposure to the stuff and it eats your liver.

Charlie Self "Politics: A strife of interests masquerading as a contest of principles. The conduct of public affairs for private advantage. " Ambrose Bierce

[Bay Area Dave]

That's why I wear the respirator! I know it's hard on your organs. I'll never forget the day I stupidly applied Deft without a respirator. I was outside and the fumes really got to me. Brushing the stuff on the inside of a cabinet was unbearable. That's the last time I'll allow myself to be exposed to that strong of a chemical like that. What IS it with Deft? It's the most noxious coating I've used so far? I've been around plenty of other bad chemicals; I'm talking for woodworking, is there a clear finish any nastier than Deft?

dave

Charlie Self wrote:

[Tom Watson]

Deft is pretty much nitro lacquer formulated for brushing.

Two part polyester urethanes and some of the other epoxy coatings are far worse.

Try some radiation cured epoxy acrylate - yum.

Regards, Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[Bay Area Dave]

does an organic respirator protect one from the 2 part poly ureas and epoxys?

dave

Tom Wats> >

[Tom Watson]

"*RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH- approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter."

from:

Tom Thomas J. Watson-Cabinetmaker Gulph Mills, Pennsylvania

[Slowhand]

What liver? ;-) SH