Author Topic: Protective finish on MDF question  (Read 21134 times)

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Offline Mauri Motti

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Protective finish on MDF question
« on: April 04, 2012, 08:03 PM »
I am doing extension (bench) wings on my miter saw out of MDF and though to myself should and could I use something to protect them? I know, I know, it's not a piece of furniture but I would like to extend their (in my use rather harsh) life as long I can.  :)

Any recommendations welcome.

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« Last Edit: April 04, 2012, 08:04 PM by Mauri Motti »

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Offline Roseland

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Re: Protective finish on MDF question
« Reply #1 on: April 05, 2012, 12:50 AM »
I spent ages making a bench top, routing it to the same pattern as my MFT before coating it with Tung oil: it bowed like a banana.  I had already laminated it to some ply underneath to make it stiffer, so I couldn't get to the other side to "balance it out".

So whatever you use, I'd make sure I treated it both sides before investing too much work in it.  (From the photos this advice might be too late!)

Andrew
TS55, MFT/3, OF1400, OF1010, CT26, RS100, ETS125, CXS, MFS400, DF-500, Zobos.

Offline Mauri Motti

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Re: Protective finish on MDF question
« Reply #2 on: April 05, 2012, 08:47 AM »
Thanks for your reply Andrew. The bench tops on both sides (other not seen in the picture) are torsion boxes. I guess Tung oil may still be an option then? I suppose the oil lays like a film on top of the MDF?

 

Offline Sometimewoodworker

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Re: Protective finish on MDF question
« Reply #3 on: April 05, 2012, 09:32 AM »
Thanks for your reply Andrew. The bench tops on both sides (other not seen in the picture) are torsion boxes. I guess Tung oil may still be an option then? I suppose the oil lays like a film on top of the MDF?
Unfortunately it won't the MDF will absorb the oil and may distort.
I would put a couple of coats of shellac on to seal the MDF then if you want a hard surface a polyurethane. The shellac will be absorbed but not nearly as much as most other finishes and will stop the other finishes soaking in but they will work well over the shellac.
Jerome
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Offline Alan m

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Re: Protective finish on MDF question
« Reply #4 on: April 05, 2012, 06:00 PM »
in this situation i would reconmend some kind of laminate put on both sides.. it will help the sliperyness too
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Offline Sometimewoodworker

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Re: Protective finish on MDF question
« Reply #5 on: April 05, 2012, 08:39 PM »
in this situation i would reconmend some kind of laminate put on both sides.. it will help the sliperyness too
Since the torsion boxes look to be finished that won't work. Will it?
Jerome
TS55, OF1400, Elu MOF96, Rotex150, DTS400, ETS150/3 Domino, MFK700, CXS, HL 850, Trend T11, Makita LS1212, Original Mini CV06 Cyclone, Workshop supplies drum sander, & WoodRat. Don't have don't want list: MFT
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Offline Alan m

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Re: Protective finish on MDF question
« Reply #6 on: April 06, 2012, 05:09 AM »
sorry . meant laminate a new piece and put that on top of the torsion box
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)

Offline Mauri Motti

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Re: Protective finish on MDF question
« Reply #7 on: April 06, 2012, 09:28 AM »
Smart thinking! Never thought about that as an option.

Offline zapdafish

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Re: Protective finish on MDF question
« Reply #8 on: July 12, 2012, 06:14 PM »
I got the cheapest  laminate flooring from home depot and covered mdf tops with that.  Some of it actually looks pretty good.

My first workbench covered with flooring  [tongue]
« Last Edit: July 12, 2012, 06:19 PM by zapdafish »
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ericbuggeln

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Re: Protective finish on MDF question
« Reply #9 on: July 13, 2012, 12:28 AM »
Call me tomorrow

ericbuggeln

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Re: Protective finish on MDF question
« Reply #10 on: July 13, 2012, 12:29 AM »
How embarrassing, i thought i was on my cell phone?!?!

Offline Peter Parfitt

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Re: Protective finish on MDF question
« Reply #11 on: July 13, 2012, 02:38 AM »
Andrew is right - treat both sides the same. I have tried many different things to seal MDF...

I used to favour shellac (I used to just brush on French Polish) but it takes a long time to dry. I then tried Danish oil which worked reasonably well. I recently reviewed Osmo oils and have spilt some on my MFT top. I think that the Osmo Top Oil would be worth a try. It is a wax based product that absorbs into the surface and it should give you a durable finish. It is then very easy to touch up or re-coat if required. Maybe some other Foggers have tried this?

Peter

Offline Timtool

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Re: Protective finish on MDF question
« Reply #12 on: July 13, 2012, 06:49 AM »
For MDF workbench surfaces i prefer oils, any other finish will get scratched and damaged and will look terrible. On my homemade MFT tops i first used a mix of turpentine and linseed oil, and later i used the surfix heavy duty oil. result seems to be pretty much identical. Mdf doesn't "work" unless you have extreme humidity variations, i only coat one side and had no problems. On a side note, when oiling mdf you need plenty coats, 3-4 and the first days it usually looks horrible untill after a few days it cures and gets a deep warm magnificent brown color.
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Offline Peter Parfitt

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Re: Protective finish on MDF question
« Reply #13 on: July 13, 2012, 07:05 AM »
I would still recommend doing both sides as MDF does absorb moisture and can warp.

Peter

Offline MarkF

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Re: Protective finish on MDF question
« Reply #14 on: July 13, 2012, 07:09 PM »
I have a ~10 year old David Marks style torsion box assembly table with a 3/4" MDF top and Mahogany skirts.  The top is sealed with a coat of Seal-a-Cell wiping varnish and a good application of paste wax on top of that.  The bottom side is raw but has a drywall screw in it about every 3 inches in each direction attaching a web frame to it.  It has stayed very flat...a few thousands +- over its 3' depth and 5' breadth in a humid garage.  If your torsion box is made well I wouldn't hesitate to do the same.

Offline Richclausen

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Re: Protective finish on MDF question
« Reply #15 on: May 26, 2017, 08:13 PM »
Hello Tim

"MFT tops i first used a mix of turpentine and linseed oil, and later i used the surfix heavy duty oil. result seems to be pretty much identical. Mdf doesn't "work" unless you have extreme humid..."

Tim what was the ratio turpentine to indeed oil please?

How do you apply it? Spray on or painting with a brush or roller?

Thank you

Richard

Offline GarryMartin

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Re: Protective finish on MDF question
« Reply #16 on: May 27, 2017, 05:39 AM »
As the thread has been resurrected, and to answer @Peter Parfitt ...

I recently reviewed Osmo oils and have spilt some on my MFT top. I think that the Osmo Top Oil would be worth a try. It is a wax based product that absorbs into the surface and it should give you a durable finish. It is then very easy to touch up or re-coat if required. Maybe some other Foggers have tried this?

I've done some tests recently with Osmo on MDF and have been very pleased. One of my goals was not only protecting the surfaces, but also maintaining the raw colour of the MDF. On the recommendation of Osmo UK and some Twitter buddies, I've settled on Osmo Polyx-Oil RAW 3044 as the first coat, followed by Osmo Polyx-Oil Matt 3062 as the second. The below photo shows the colouration in a sample board.

RAW 3044 uses a small amount of white pigments to "neutralise the permanent 'wet-look' that develops after application of a clear finish" and really helps to keep the MDF close to the, well, raw colour.  [wink]

"Osmo Polyx-Oil is developed from natural oils and waxes to provide the most hardwearing and durable protection for wooden flooring and furniture..." so I've no doubt it will stand up well to shop use.