Gluing Masonite

[Lou Park]

With all my years of woodworking and carpentery, I almost never use masonite for anything. I'm trying to glue masonite to pine to create the curves for my tear. I've looked at the "glue this to that" (I love that site),
and don't come up with a good gluing idea. What is the best glue to use to
attach masonite to pine? Each time I do this, I can pull it apart with little pressure. What do other people use?
Lou

[kennyrayandersen]

With all my years of woodworking and carpentery, I almost never use masonite for anything. I'm trying to glue masonite to pine to create the curves for my tear. I've looked at the "glue this to that" (I love that site),
and don't come up with a good gluing idea. What is the best glue to use to
attach masonite to pine? Each time I do this, I can pull it apart with little pressure. What do other people use?
Lou

Lou -- I'm with you - I never touch the stuff. What have you tried -- epoxy, elmers/titebond? Does the Masonite come apart, or does the glue just not stick? Did you prep the Masonite surface by sanding it with some 80 grit? Usually adhesive failures are do to inadequate surface prep. The Masonite may also have a release agent on it so it comes of the press easily -- you'll need to scuff that up and clean it with something like acetone or another solvent (I think MEK, which was used in the old days, is pretty nasty, but a little acetone might do the trick) before gluing it together.

[aggie79]

I use Masonite for for jigs. If it is just single-tempered (smooth side), I adhere the "waffle" side using a polyurethane construction adhesive like PL Premium. For double-tempered, I roughen the surface with 60 or 80 grit, then use the same adhesive.

On my teardrop, I used 3mm (1/8") Russian Birch plywood for the curved areas. My front roll pan has a 6" radius, and it was a bear to get in place. My hatch has a 10" radius and it wasn't a problem.

[Lou Park]

Lou -- I'm with you - I never touch the stuff. What have you tried -- epoxy, elmers/titebond? Does the Masonite come apart, or does the glue just not stick? Did you prep the Masonite surface by sanding it with some 80 grit? Usually adhesive failures are do to inadequate surface prep. The Masonite may also have a release agent on it so it comes of the press easily -- you'll need to scuff that up and clean it with something like acetone or another solvent (I think MEK, which was used in the old days, is pretty nasty, but a little acetone might do the trick) before gluing it together.

So far, Masonite doesn't seem to come apart from glue. I have used liquid nail, PL premium, Pl 200, Ace Hardware brand and it just doesn't hold. I contacted Liquid nail and they recommend their premium, but to trowel it on. That kinda defeats a purpose. The stuff just comes apart if you even bump it, and yes I even glued the rough side. So far the stuff that stays put is contact cement.
Lou

[Arne]

My thought is that because of the construction of Masonite, and the materials used in it, it would be very difficult to do anything with it without using some type of mechanical fasteners. It is just mush dried out.. and when it gets wet, it turns back into mush.

[Lou Park]

It is just mush dried out.. and when it gets wet, it turns back into mush.

Actually, I took a couple of small peicess of masonite and soaked them in water for 2 weeks. It left a ring around the sink. One peice was a whole lot harder to break apart than I thought. The other I let dry out with a fan for a couple of days and it was as good as new. It did however gain 50% weight when water logged.
Lou

[Arne]

well, then, go ahead and glue it. And good luck.

[bdosborn]

I used masonite on the teardrop and had pretty good luck with gorilla glue and staples. But, it was never as strong as I would have liked it to be.



Bruce

[tinksdad]

Masonite and TiteBond.....haven't had a problem yet. I did seal the living beejesus out of the masonite before I prepped and painted and the edges do have aluminum molding screwed every 6 or 8 inches.

[DesertSkies]

I decided to use PL Premium.

After talking to the manufacturer, it sounds like PL might work a little better. I'll be gluing masonite over ply and spars. The very hot and dry climate severely cuts the working time of TB. Liquid Nails says that they don't recommend their product for Masonite.

I tested the bond by gluing and stapling a piece of Masonite to curved ply like my walls. It seemed to work fine.

I had hoped to remove the staples but they went in below the surface leaving a clean hole and they were impossible to dig out with any tool I could find.

I've seen many opinions about stapling with or without leaving them, screws, strapping, etc.

My finish will be CPES or epoxy. I still haven't made up my mind.

Any opinions for my current build?

[afreegreek]

a hard glue such as white/yellow carpenter's glue (PVA) or epoxy won't work so well for stressed skins (curved). it's ok for flat panels though.. your best bet is something like PL Premium, Liqud Nails etc., or a good contact adhesive such as Sta-put.

the best method to attach is a fine wire stapler (upholstery).. they have a wide crown (approx. 1/2") and are very fine wire.. about 21-22 gauge. they are like the difference between an 18 gauge brad nailer and a 23 gauge pin nailer.. you can get a cheap one for less than a hundred bucks new..

http://grexusa.com/grexusa/products.php5?id=80AFLM

you can staple directly into the material and leave them, they will set below the surface or you can staple through some nylon banding and pull them all at once. the hole is tiny and needs no filler.. they come in leg lengths up to 9/16" and have tremendous holding power.. they are particularly effective with thin materials..

[kennyrayandersen]

I decided to use PL Premium.

After talking to the manufacturer, it sounds like PL might work a little better. I'll be gluing masonite over ply and spars. The very hot and dry climate severely cuts the working time of TB. Liquid Nails says that they don't recommend their product for Masonite.

I tested the bond by gluing and stapling a piece of Masonite to curved ply like my walls. It seemed to work fine.

I had hoped to remove the staples but they went in below the surface leaving a clean hole and they were impossible to dig out with any tool I could find.

I've seen many opinions about stapling with or without leaving them, screws, strapping, etc.

My finish will be CPES or epoxy. I still haven't made up my mind.

Any opinions for my current build?

The upper skin will have to support human loads which even the 1/8 plywood could do with close spaced internal stiffeners. However, I’ve found that there is usually a bit of a premium on some of the thinner material, so if the upper sheet will be a ¼ inch think you should check to make sure ¼ inch thick isn’t actually cheaper than using (2) 1/8 inch sheets; plus, the ¼ inch thick sheet is MUCH stronger than 2 1/8 inch sheets (not to mention that the deflections will be much less.
I would say especially since you are using Masonite that you should use epoxy and fiberglass before the final UV protecting paint. ANY kind of moisture leak will be intolerable to the integrity of your structure. So, you can cover it with aluminum, or fiberglass (I could have missed where you said you were going to do that), but you will really need to make sure NO water gets in.

[DesertSkies]

you can staple directly into the material and leave them, they will set below the surface or you can staple through some nylon banding and pull them all at once.

AFG, that's a great idea. I wish I had read it BEFORE i attached the roof!

The staples I used are about 1/4 x 1/2 or so. With the pressure correctly adjusted they sank just below the surface and held pretty well. I did notice that the staple holes tend to stick out and need to be sanded down a little before filling with epoxy putty.

The PL worked very well. I had good luck getting a good bond with staples, a little clamping here and there and some weights over the vent space just in case. My roof went on in two panels and there was adequate time to get it right without the glue "skinning over." I was able to clean the runout with a scraper, rags and a little mineral spirits.