Gluing Hardboard

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I was trying to make a jig the other day, and I needed to glue together two pieces of 1/4 hardboard. I have the kind that is only smooth on one side, and I was trying to glue together the rough sides with wood glue.

It didn't work so well. The glue came apart.

I've read of people gluing hardboard together with contact cement, but I think that would only work if I were gluing together two flat sides, not two rough sides.

Do I need to go back and buy double-sided hardboard, or is there a way to glue this stuff together?
 
I prefer service tempered hardboard (smooth on both sides) but have used regular hardboard as well. I've laminated the rough side to ply and to solid woods witout a problem. I have not laminated the two rough sides together before.

I would assume the failure was due to the absorption of the 'open' rough side material creating a starved joint(?). I would mix up some glue-size by adding some water to the glue you plan to use, stir well and brush a thin coat onto one or both rough surfaces. After about an hour, apply your (un-thinned) glue like usual and clamp it up for a few hours. If your test piece works, I'd leave the production piece clamped overnight just to be sure.
 
Maybe I just didn't keep it clamped up long enough. I followed the instructions on the glue bottle, which said to keep it clamped for half an hour.
 
I prefer service tempered hardboard (smooth on both sides) but have used regular hardboard as well. I've laminated the rough side to ply and to solid woods witout a problem. I have not laminated the two rough sides together before.

I would assume the failure was due to the absorption of the 'open' rough side material creating a starved joint(?). I would mix up some glue-size by adding some water to the glue you plan to use, stir well and brush a thin coat onto one or both rough surfaces. After about an hour, apply your (un-thinned) glue like usual and clamp it up for a few hours. If your test piece works, I'd leave the production piece clamped overnight just to be sure.

Glenn, I think you are on the right track about starvation and going with the sizing, Buuuuut......I seem to remember seeing something on one of the TV shows (not using hardboard, just a porus wood), and they said let the sizing set about 10 to 15 min max (IIRC), and then apply normal glue and clamp it up. I got the gist that if the sizing sets too long it will get hard and you don't get any action between the normal glue and the material being glued up, (ie: hardboard/wood/leather, etc.) and the only action would be between the new glue and the sizing and it doesn't stick to itself that well after it gets hard, at least not as good as it would bond to raw wood or the other materials I mentioned.:dunno:

Please NOTE, that I have not tried gluing hardboard to hardboard either, so this answer is NOT from personal experience. I have glued a good bit of hardboard to wood, and MDF with good results but I always made sure I had PLENTY of glue on the hardboard and wood or MDF, and I also think he needs to let it set in the clamps for a longer time, expecially if the temperature is cool.

Anyhow, some new ideas to play with.
 
they said let the sizing set about 10 to 15 min max (IIRC), and then apply normal glue and clamp it up. I got the gist that if the sizing sets too long it will get hard and you don't get any action between the normal glue and the material being glued up

Thanks Norm. I'm good with that info. Makes sense to me. Never hesitate to jump in on anything I'm offering advice on. The more the merrier and I have been known to be just plain wrong sometimes ;-)

I have glued a good bit of hardboard to wood, and MDF with good results but I always made sure I had PLENTY of glue on the hardboard and wood

That spells out my actual experience as well; I use a chip brush or a small roller to spread out the glue. I should also state, for Porter, that I get my best results when I do these laminates over-size. I cut the pieces to dimensions once they are dry.
 
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