Thread: A dumb question

Good question Noel,
I really don't know but maybe it's because the MDF soaks up the glue,
similar to the way it soaks up paint and you have to coat it a few times to cover it.
Looking forward to hearing what others say.
Cheers, crowie

Originally Posted by Trustinggibbsie

Hello.......I am using MDF for the first time (as far as I can remember anyway) - usually I use solid timber, or at least ply. But the glue on the MDF seems to take longer to grab. By this I mean that when gluing fiddly bits I usually wait for the glue to grab before clamping. This ensures that the work piece doesn't slide around. Well, as I say, with the MDF it seems to be taking longer to "grab". What I would like to know is, does normal wood glue work as effectively on MDF as solid timber?

Thank you

Noel

Hi Trusting.......,

The surface of MDF has wax impregnated into it during the manufacturing process. It's called slack wax and it is there to prevent the pressed sheets adhering to the platens in the pressing process. The presence of this wax will inhibit the successful gluing action with many glues, The secret is to use AV 180 cross linked and enhanced PVA glue. That product is formulated to overcome the wax issue and it also grabs quite quickly particularly as its shelf life gets out towards its use by date. It's available in good hardware stores or from Laminex Industries in retail quantities.(500ml bottle) It's quite expensive but also excellent for general solids timber gluing and doesn't form a fine red line when edge gluing Huon Pine as is the case with some marine epoxies.

Cheers Old Pete

Thanks for the replies, Pete and Crowie. Old Pete, this project is about 2/3rds finished and I'm wondering if I will have to re make it? It is only a small thing requiring no great adhesive strength, I would have thought. It is a small wishing well, about 18" high, and will be used as a decoration at a wedding. It is used to put small envelopes and the like in, that's all. Do you think the PVA glue would do a satisfactory job in this case? Where it has been possible I have also used small nails, but that's not always possible.

Noel

Hi Again Trusting.... Yes I'm sure ordinary PVA glue will be just fine for an application that does not need to exhibit any structural attributes.

Cheers Old Pete

Thanks for your help, Pete. I've made a note of the AV180 for the next time I use MDF.
Noel

Would sanding the section where they connect help?

Sanding might help but usually I only use a decent PVA glue and had no trouble with the glue failing so far.

Hi,
I asked a similar question:
https://www.woodworkforums.com/f198/mdf-mdf-136613/
ended up just sanding, worked O.K.
Bob H.

This thread was helpful to me, and to Old Pete, I used to collect 22 tonnes of slack wax from the Adelaide Refinery (Stanvac) when I drove the Big Jiggers way back in the 1990's. I never knew it was used for making MDF. I used to fill the demountable container tanker, and then put it on a trian to somewhere. . . .