Strong Glue for wood to masonite

[Bob Carnie]

I have a project where I need to bond a print that is mounted on masonite, to a soft wood box. After the bond we leave weights on it over night.

We currently are using Weldbond non toxic glue, but it is not giving a complete bond.

We have also tried PL fast grap adhesive but it is so thick it leaves gaps.

Any suggestions on a stronger glue that would work for the above application??

 

[NormanV]

Most wood glues will do that successfully. Are you just putting a few weights on it? Probably the Masonite (hardboard in the UK) is warping due to the moisture in the glue. What you need is something to spread the weight over the whole surface in order to achieve complete contact.

 

[Rick A]

Try Gorilla glue, its polyurethane base, and in my experience, will bond anything. Best results are obtained with dampening the surfaces to be mated, as the stuff is moisture reactive. A word of caution, it foams and will extrude from the sides that are exposed so paint(or spread)sparingly.

 

[waynecrider]

Woodworkers use Titebond II or III for cabinet work. Good bonding is all in the preparation and clamping. Allow 24 hrs for a complete bond.

 

[Barry S]

I use Titebond II for that kind of work and as Norman and Wayne mentioned, make sure you clamp adequately with even pressure across the full surface of the bond.

 

[Rick A]

If the masonite is hardened on both sides regular wood glues will not hold, ad there is oil in the finish of the masonite. I've used Gorilla glue to bond melamine panels together, no other adhesive will do that.

 

[MSchuler]

You might try roughing up the back of the masonite with sandpaper to get better adherence.

Hide glue is a traditional approach that takes a little work: you soak the glue pellets, heat them to 140 degrees in a waterbath and then apply. The benefits are that it tacks very quickly but is initially repositionable, is reversible through reheating (though this might not be easy with a photo involved) and cleans up very easily.

 

[Dinesh]

You may want to try contact cement.

 

[mark]

What is not bonding? Is it the print to the masonite, or is it the masonite to the soft wood. These are two different scenarios requiring two different methods.

If it is the masonite to soft wood. I have an issue with anything that calls itself a "universal adhesive" and would just get rid of the stuff you are trying to use. IMO this is code for won't adhere to anything. My standard wood glue is titebond. If you need work time they have one that does not set up immediately. I have had some issues with Masonite unless I rough scuff the hell out of it and even then it can be troublesome. I have never had an issue with epoxy coming undone. No matter what glue you are using make sure the surfaces of each board are scuffed and glue spread evenly. Some would say put glue on both pieces.

Just putting weights on the piece over night is probably not enough weight unless you are talking several hundred pounds. Get some clamps and cross pieces. For wide lamination I have used 3/8 steel bar as cross pieces when clamping.

 

[waynecrider]

On further review many people use contact cement. If you use glue you'll have to size it first as it will suck the glue up. It seems alot of people use screws in addition.

 

[Jon Shiu]

I'd be wary of any water based adhesive or technique as Masonite can warp.

Jon

 

[greybeard]

I've made a number of lensboards by laminating 1/4" Masonite, using two squares of slightly different sizes for an "instant rabbet". None has ever shown signs of failure, and they were all assembled using Weldwood resin glue waterproof, resorcinol-formaldehyde). This glue was, according to legend, developed originally for assembling Supermarine Spitfires during WWII. The fact that it is still in production (aircraft, boats, furniture, etc.) must say something about its utility. It is mixed with water to a thick-cream consistency, and cures by chemical reaction, not cooling or drying. The desired glue thickness is not large, and nearly all of the water is consumed in the curing reaction, so differential swelling of the wood is not a big issue.

My lensboard assemblies never warped, possibly because I either clamped them securely or used heavy weights. For a large area, I would probably just go and pick up several bags of sand from the local building supply, and use something very flat and stiff (like 1-1/8" decking plywood) to support the work.