Is there a trick to get an invisible join? Arghh

[CantReallyDecide]

We have put two pieces of MDF together to form a desk, I thought I could fill and rub down to hide the join but it looks terrible, any clever suggestions would be appreciated? Thanks

Get a single piece of MDF for the enter top.

You will never make it look that neat by filling it even if it is colour matched.

The other alternative is to get a t - piece shaped strip of plastic and put that in the gap. That will make it look tidier. But the surface will be uneven.

You can probably get some sort of thick white tape to put over it as well. A bit like veneer tape or trim.

The other issue you’ll have with wood is that it will invariably expand and contract slightly through the year, so any wood filler or such that you use to join the pieces will eventually look crap as it cracks and breaks off secondary to this. As above, your options really are get a new single sheet of mdf that does the job, use a t strip or similar tape to cover or just put up with it as a bit of a bodge job.

That's a big gap and it's been filled badly. Are you using a proper wood filler? The information above is strictly speaking correct because MDF doesn't expand and contract like wood - it's very minimal. There's no reason why you shouldn't be able to build up layers of fillers and sand to get it properly flat, then paint over it all to get a much more discrete join. It's just about time and patience.

I would sand it down and cover with fablon. Preferably with some sort of pattern so the join doesn't show up so much.

I meant ISN'T strictly speaking correct

Personally I’d put a “top” on top.

you are never going to fix that.
you need one piece

I’d get some good, old fashioned, blue peter style, sticky back plastic on that.

You can get that sticky plastic rolls (Fablon), in all sorts of colours and patterns and cover the whole top, just use white if you like. I would run it back to front and over the lip underneath at the front to make it neat. Having first made the join as tight and level as possible.

Put a piece of ply over the whole thing.

If both pieces of MDF are level and have straight edges where they butt together there should be minimal join showing. How have they been fixed together? Dowels, biscuits, just glue??

It’ll still expand and contract and also I’d put money on it that the way that’s been built there’ll be some movement too from people leaning on it, sitting on it perhaps, heavy computers and so on. Bottom line is any wood filler in something like that is going to get disturbed and it’ll look crap given a few months. Another option OP would be to get some sort of stick on vinyl or similar cover it all. You can get it very cheaply from places like B&Q - we used some to freshen up our kitchen counters and it actually comes out very nicely.

thank you very much for all the helpful comments, fablon shopping today, thats a really great idea and one I hadnt thought of, thank you