The Framers Forum

I have had a problem in joining the mitres of what appears to be LDF \ MDF mouldings. What is the best glue solution to use before underpinning. Under pinning alone doesnt work as using PVA then underpinning.

Cheers
Len

Sounds like emafyl to me - join using superglue - I have noticed a few moulding companies offering this at the moment - its cheap - and has its place - but i dont use it - no matter how hard you try, you will find that the material has so much flex that unless you only make small frames it has a habit of cracking on the corners - i am sure others think its the best thing since sliced bread.

I gave up on this MDF stuff, Len.

I never did find a satisfactory way of joining it. It proved to be deceptively solid and dense. Very often when driving one wedge on top of another there would be so much resistence that the wedge would split.

So if there is anybody out there who knows how to get a good join, please share with us.

Biscuit joiner and clamps…..is it worth it!!!

Hi All,

I have basically two rules of thought here:

1. If I have to use these type of mouldings, I either use an Impact Adhesive, or I have discovered a product called 'No Mare Nails', seems to work, no complaints so far, or failing that 'Gripfill', wonderful stuff!

2. DONT offer any of this type of moulding on your chevron board, then the problem will never arise

As for trying to underpin MDF, as John says its next to impossible, you can only really get one wedge in and are then hoping for the adhesive method to work and hold.

Steven
(SquareFrames)

For some years now I have been using a two-part isocyanate glue from Lion Picture Framing Supplies, Birmingham, for almost everything. Using this product you have 3-4 seconds to adjust the joint before the glue sets (so do a trial fitting first without glue) and then it is fully set in 10-15 seconds depending on air temperature. It is not so good on pine mouldings which appear to have a surplus amount of resin on the cut ends - but it has worked well on MDF. I don't sell MDF or plastic mouldings but customers bring the plastic variety for repair from time to time - these are the mouldings that look like a "Crunchie" bar in cross section, with lots of tiny air bubbles. I put plenty of activator on one part and lots of the glue on the other half so that surplus glue fills the holes in both halves (but doesn't squeeze out to the front of the frame - 'cos it won't come off!!). When underpinning (even with great care using a hand-operated underpiner) this plastic is inclined to crumble a bit. However, the crumbling occurs on the back of the frame. Simple fill the hole(s) afterwards with the glue and drip a couple of drops of activator on to it and leave for a minute or two to let it harden like a filler.
Needless to say, if a customer brings in a "dodgy" frame of this sort which may not survive "repairs" I accept the order only at the customer's risk.