Author Topic: How to seal mdf edges?  (Read 12751 times)

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Offline Acrobat

  • Posts: 464
How to seal mdf edges?
« on: October 13, 2015, 07:36 PM »
Hi, I've scoured the net as you do, and there are rather a few conflicting ways and various methods to deal mdc edges for spray painting.

I read that some use 50-50 mix of pva and water and paint this on the edges, let dry, sand with fine grit 320, then prime, and finally paint top coats.
I would have thought adding any water to the edges of mdf would likely make the swell? I'd be sceptical if this is ok?
But since I have both pva and water on hand would be willing to try it.
Otherwise any other advice on sealing products is welcome.

I have many oval shapes-all edges to paint, so not a typical flat edge like a bookshelf. I just want a lovely smooth finish all over when done and not to be able to easily tell the edge from any flay surtace. (Imagine a pair of sunglasses).
Don't wake me, I'm livin' the dream!

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Offline Brandon

  • Posts: 214
Re: How to seal mdf edges?
« Reply #1 on: October 13, 2015, 08:31 PM »
Which variety of mdf did you use? If putting a profile on mdf I'd suggest using a "double refined or premium" mdf. My suppliers use different names for essentially the same thing. It's a much denser product and takes paint well with only a some minimal sanding. I use it as an inexpensive alternative for painted raised panel doors.

Offline bkharman

  • Posts: 1983
Re: How to seal mdf edges?
« Reply #2 on: October 13, 2015, 08:34 PM »
Get a small can of Zinnser BIN shellac. It is paint and shellac in one. I use it on MDF as it is alcohol based and therefore no water to swell the edges up. It dries very hard and is also sands to a powder. My steps would be:

1. Prime the edges with BIN (you don't have to be perfect as it will sand easily.)
2. Sand lightly with a soft sanding block or profile to reduce the fuzz and BIN.
3. Clean up dust and coat again.  Do as many as you feel get you the edge you want.

A couple of notes. Buy a bunch of 1" foam brushes. It is a lot cheaper than trying to use denatured alcohol to clean things. Use the brush then toss.
BIN will dry to the touch in a matter of minutes. Generally between 5 and 15. You have to work quick.
Don't work out of the BIN can... Pour a little in a working jar and keep the main can lid tight when not pouring. I use a mason jar and put the lid on loosely as I work. The alcohol starts evaporating immediately. Once I forgot to put the lid on the mason jar and put a foam brush in it. 30 minutes later I had a almost hard goopy jar with a foam brush stuck in it.

I love the stuff but it has a slight learning curve. The good news is if you mess up and have drips and such, it sounds out easily and to powder.

Don't hesitate to ask if you go with it and have any more questions. I prefer this method over the glue mix EVERY time.

Cheers. Bryan.
People, I just want to say, you know, can we all get along? Can we get along?

Offline tjbnwi

  • Posts: 5605
  • Cedar Tucky Indiana
Re: How to seal mdf edges?
« Reply #3 on: October 13, 2015, 08:40 PM »
I've used the water/glue combo, it works well.

As Bryan posted, BIN is a great product for your application also.

I now use Kem Aqua Surfacer when I spray anything MDF.

Tom

Offline Billedis

  • Posts: 608
Re: How to seal mdf edges?
« Reply #4 on: October 13, 2015, 09:07 PM »
I have had good results with just plain old drywall mud.  put it on, let it dry and sand it off.  Bill

Offline Matthewajones

  • Posts: 206
Re: How to seal mdf edges?
« Reply #5 on: October 13, 2015, 10:17 PM »
You can also use bondo glazing putty. It comes in a tube and can be found wherever bondo is sold. It dries quickly, sands well and I apply it with my finger. It is also red, so you will end up with red fingers.

Offline sae

  • Posts: 841
Re: How to seal mdf edges?
« Reply #6 on: October 13, 2015, 10:38 PM »
You can also use bondo glazing putty. It comes in a tube and can be found wherever bondo is sold. It dries quickly, sands well and I apply it with my finger. It is also red, so you will end up with red fingers.

@monstrol

There's so many less volatile fillers in this world, I don't know what the obsession is with woodworkers and Bondo.

Bondo contains just about all the things that will end your life in a hurry, yet people continue to flock to it (and recommend it).

Read the MSDS, and then throw it all away. And certainly don't use your fingers to apply it.

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn_zu8l00xM8tvmxm95v70k17zHvu9lxtD7SSSSSS--

Offline tjbnwi

  • Posts: 5605
  • Cedar Tucky Indiana
Re: How to seal mdf edges?
« Reply #7 on: October 13, 2015, 11:45 PM »
You can also use bondo glazing putty. It comes in a tube and can be found wherever bondo is sold. It dries quickly, sands well and I apply it with my finger. It is also red, so you will end up with red fingers.

@monstrol

There's so many less volatile fillers in this world, I don't know what the obsession is with woodworkers and Bondo.

Bondo contains just about all the things that will end your life in a hurry, yet people continue to flock to it (and recommend it).

Read the MSDS, and then throw it all away. And certainly don't use your fingers to apply it.

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn_zu8l00xM8tvmxm95v70k17zHvu9lxtD7SSSSSS--

He's calling it Bondo, but it is really automotive glazing compound he is recommending.

Could be worse, I still lead body seams.

Tom

Offline NL-mikkla

  • Posts: 256
  • www.m144h.com
Re: How to seal mdf edges?
« Reply #8 on: October 14, 2015, 12:50 AM »
Up here there are a few brands that have a specific product for that, it's usually just called edge sealer.
They work really well, create the edge you describe, dries within 15 min or so and sand to dust.
Pretty sure your local painstore can help you with that.

Offline Acrobat

  • Posts: 464
Re: How to seal mdf edges?
« Reply #9 on: October 14, 2015, 04:34 AM »
Thank you guys. I've gone to the paint dept and got some zinsser BIN sealer. Will try it tomorrow after work. Not cheap stuff but if it works better than primer paint I have tried previously It will be worth it. The other stuff seems to need a heap of coats on the edge and if I can avoid that it will save time and top coat wastage.
Don't wake me, I'm livin' the dream!

Offline bkharman

  • Posts: 1983
Re: How to seal mdf edges?
« Reply #10 on: October 14, 2015, 07:57 AM »

Thank you guys. I've gone to the paint dept and got some zinsser BIN sealer. Will try it tomorrow after work. Not cheap stuff but if it works better than primer paint I have tried previously It will be worth it. The other stuff seems to need a heap of coats on the edge and if I can avoid that it will save time and top coat wastage.

It is very thin material so make sure you have a drop cloth under the work.

Ain't cheap but I love the stuff!!

Oh, the smell. It will have a real strong smell but it disappears pretty quick.

Cheers. Bryan.
People, I just want to say, you know, can we all get along? Can we get along?

Offline John_

  • Posts: 159
Re: How to seal mdf edges?
« Reply #11 on: October 14, 2015, 10:10 AM »
You can also use bondo glazing putty. It comes in a tube and can be found wherever bondo is sold. It dries quickly, sands well and I apply it with my finger. It is also red, so you will end up with red fingers.

^^^^ +1

Bondo 907 Glazing and Spot Putty
http://www.amazon.com/gp/product/B0002JM8PY?psc=1&redirect=true&ref_=oh_aui_search_detailpage

Offline Cheese

  • Posts: 4673
Re: How to seal mdf edges?
« Reply #12 on: October 14, 2015, 11:15 AM »

Could be worse, I still lead body seams.

Tom

Seriously???

Offline w802h

  • Posts: 216
Re: How to seal mdf edges?
« Reply #13 on: October 14, 2015, 06:15 PM »
I know a guy who builds a lot of cabinetry and decided to buy an edgebander for taming MDF edges. 

Offline tjbnwi

  • Posts: 5605
  • Cedar Tucky Indiana
Re: How to seal mdf edges?
« Reply #14 on: October 14, 2015, 10:26 PM »

Could be worse, I still lead body seams.

Tom

Seriously???

Yes...

I thought my oldest daughter how to body solder.

I'll get some picture of the paddles, files, tallow and bars.

Tom

Offline Cheese

  • Posts: 4673
Re: How to seal mdf edges?
« Reply #15 on: October 15, 2015, 03:32 AM »
That's pretty cool Tom...a forgotten art.

Offline Matthewajones

  • Posts: 206
Re: How to seal mdf edges?
« Reply #16 on: October 15, 2015, 09:25 AM »
Also....Mohawk makes a water-based grain filler that is a pain to use but gets the job done...
you know for those that are kinda shy of aromatic hydrocarbons.

Offline Dbn107

  • Posts: 19
Re: How to seal mdf edges?
« Reply #17 on: October 15, 2015, 05:03 PM »
Thinned Timbermate works pretty well too.

Offline Acrobat

  • Posts: 464
Re: How to seal mdf edges?
« Reply #18 on: October 20, 2015, 04:15 AM »

Thank you guys. I've gone to the paint dept and got some zinsser BIN sealer. Will try it tomorrow after work. Not cheap stuff but if it works better than primer paint I have tried previously It will be worth it. The other stuff seems to need a heap of coats on the edge and if I can avoid that it will save time and top coat wastage.

It is very thin material so make sure you have a drop cloth under the work.

Ain't cheap but I love the stuff!!

Oh, the smell. It will have a real strong smell but it disappears pretty quick.

Cheers. Bryan.

Bryan, it worked well. Think I will use it from now on. And yeah, man that does have a strong smell. Job came out with a much better finish than previously so am very happy. Thanks again for the advice and everyone's input.
Don't wake me, I'm livin' the dream!

Offline bkharman

  • Posts: 1983
How to seal mdf edges?
« Reply #19 on: October 20, 2015, 01:18 PM »


Bryan, it worked well. Think I will use it from now on. And yeah, man that does have a strong smell. Job came out with a much better finish than previously so am very happy. Thanks again for the advice and everyone's input.

The smell is strong but doesn't linger too long. I use that on MDF all of the time. If you can deal with the smell and the price, it will treat you very well!!

Glad it worked out for you @Acrobat.

Cheers. Bryan.
People, I just want to say, you know, can we all get along? Can we get along?

Offline Pnw painter

  • Posts: 151
Re: How to seal mdf edges?
« Reply #20 on: October 23, 2015, 01:39 AM »
Make sure to wear a respirator if you're using BIN. You also need to change the cartridges quite often when using it as well.

Offline bkharman

  • Posts: 1983
Re: How to seal mdf edges?
« Reply #21 on: October 23, 2015, 12:14 PM »

Make sure to wear a respirator if you're using BIN. You also need to change the cartridges quite often when using it as well.

Can I ask why?  Maybe I need to clarify but this is BIN shellac, not oil based.

If I was in a small room I could see that helping but I didn't think that the denatured alcohol was too harmful.  I keep things ventilated and never felt dizzy but that is just me.

If there are specific reasons, please share as I don't want to put myself at risk.

Cheers. Bryan.
People, I just want to say, you know, can we all get along? Can we get along?

Offline mike_aa

  • Posts: 1030
Re: How to seal mdf edges?
« Reply #22 on: October 23, 2015, 12:35 PM »
@bkharman

I'm not in a position to answer your question directly, but I thought taking a look at this link to the BIN safety sheets might be helpful.

Mike A.

Offline bkharman

  • Posts: 1983
Re: How to seal mdf edges?
« Reply #23 on: October 23, 2015, 12:46 PM »

@bkharman

I'm not in a position to answer your question directly, but I thought taking a look at this link to the BIN safety sheets might be helpful.

Mike A.

Thanks Mike. I took a look through some of the sheets and for the gallon size and rolled or brushed it doesn't seem so bad. Like I said, I generally work in a large open, well ventilated area so for me a respirator seems unnecessary but I agree anything with fumes should be handled accordingly.

I can see if you were spraying either with HVLP or aerosol that things would be different.

Cheers. Bryan. 
People, I just want to say, you know, can we all get along? Can we get along?

Offline Jimmy FineCut

  • Posts: 274
Re: How to seal mdf edges?
« Reply #24 on: November 07, 2015, 02:49 PM »
Get yourself some of this @Acrobat

http://www.edgeband.co.uk/paintable-edging-pre-glued.html

That is if you can get it in middle earth?   [wink]

Offline Acrobat

  • Posts: 464
Re: How to seal mdf edges?
« Reply #25 on: November 09, 2015, 04:18 PM »
Hi Jimmy
Thanks for the heads up, but the projects I'm making are all rounded surfaces no flat edges, so probably great for bookcases etc, may not be the right product for this. I've no idea if its available down here in hobbit country but if I need any for future I'll check it out. cheers
So far the zinsser product is working well and easy to apply with a good result.
Don't wake me, I'm livin' the dream!

Offline Jimmy FineCut

  • Posts: 274
Re: How to seal mdf edges?
« Reply #26 on: November 10, 2015, 04:00 PM »
Hi Jimmy
Thanks for the heads up, but the projects I'm making are all rounded surfaces no flat edges, so probably great for bookcases etc, may not be the right product for this..

O yea you did mention that in your first post,  I should have read it all really  [blink]

Good to hear the zinsser is working for you. I also use it for the odd job and it works a treat.