# Wood Fill or spackle for molding (mdf) seams



## 123pugsy (Oct 6, 2012)

harpua728 said:


> I am attaching two pieces of MDF molding together since the pieces I have are not long enough to cover the entire wall. What's the best way to cover the seam where the two pieces will meet....wood fill or spackle (or something else)? The MDF is only 1/4 inch thick so it will be tough to secure the joint.
> 
> 
> Thanks


The joint should be cut at a 45° angle.
Any gap, use painters caulk.


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## lenaitch (Feb 10, 2014)

+1 on the 45* joint. Wood filler is harder to sand and you run the risk of altering the profile of the mdf in the process. I am a convert the drywall patch ('spackle') as a result of comments on this site. Caulking can work but I've never had much luck making it look as good.


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## woodworkbykirk (Sep 25, 2011)

painters caulking can and will shrink.. drydex spackle is the best thing for mdf. its more stable and wont shrink


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## harpua728 (Jul 13, 2015)

woodworkbykirk said:


> painters caulking can and will shrink.. drydex spackle is the best thing for mdf. its more stable and wont shrink


Thank you. SO that's better than wood fill in your opinion? Should I use that for nail holes as well?


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## carpdad (Oct 11, 2010)

45 deg cut is called scarf joint, search and see how. It's best because when trim moves it shows the least joint. I would practice getting the miter joint as exact as you can and skip the filler because filler would accentuate the joint than hiding it. Filler will not make it look like one piece trim when the joint eventually opens. When painting it, it can hold extra paint then drip so extra eye there.


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## Yodaman (Mar 9, 2015)

I have always used wood glue and a couple brads to hold the miter joint tight while the glue dries. I have never tried spackle. It does have some adhesive in it but not likely to be as strong as glue, but I am sure it does a better job as joint filler if your miter is not perfect.

I have heard of some folks actually gluing the pcs together prior to install. Seems a little counter productive to me. If you are going to take the time to glue, set and clamp a joint why not just do it at installation.

Try to position the miter in the least obvious sight line.


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## harpua728 (Jul 13, 2015)

carpdad said:


> 45 deg cut is called scarf joint, search and see how. It's best because when trim moves it shows the least joint. I would practice getting the miter joint as exact as you can and skip the filler because filler would accentuate the joint than hiding it. Filler will not make it look like one piece trim when the joint eventually opens. When painting it, it can hold extra paint then drip so extra eye there.


Should I miter and bevel the cut, or just bevel? Basically, when I am looking at the seam straight on, should the seam be straight up and down like this (where the "I" is the seam and the dashes (---) are the pieces of MDF:

-----I-----

or should the seam look like this from straight on...

----/-----

Thanks


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## 123pugsy (Oct 6, 2012)

harpua728 said:


> Should I miter and bevel the cut, or just bevel? Basically, when I am looking at the seam straight on, should the seam be straight up and down like this (where the "I" is the seam and the dashes (---) are the pieces of MDF:
> 
> -----I-----
> 
> ...


If it was a baseboard, looking down would look like this. ----/-----


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## TimPa (Aug 15, 2010)

+1 on the wood glue. after getting the joint as good as possible, i sand it which fills any imperfections with sawdust.

also, i select where on the wall the joint goes, so that the top piece gets nailed in right at a stud.


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## 123pugsy (Oct 6, 2012)

TimPa said:


> also, i select where on the wall the joint goes, so that the top piece gets nailed in right at a stud.


I like this. Thanks. I have a big baseboard project starting soon.


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## ryansdiydad (Aug 16, 2015)

TimPa said:


> +1 on the wood glue. after getting the joint as good as possible, i sand it which fills any imperfections with sawdust.
> 
> also, i select where on the wall the joint goes, so that the top piece gets nailed in right at a stud.


+2 on the glue and +1 on sanding and the sawdust helping to fill some of the imperfection.. I glue before install as it tends to give me better control on the joint and I dont have to worry about dealing with any imperfections on the floor or wall making it harder to get a good tight seam.. Just makes sense to me...

If you still end up with a visible seam larger than you want, I also +1 on the no-shrink spackle.. for minor imperfections and nail holes.. so easy to work with and sand... 

This one probably obvious but also consider where the seam is. Dont put it in the middle or most visible spot.. if you can try to put it in an area that just won't get as many eyeballs on it..


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## harpua728 (Jul 13, 2015)

Thanks. Unfortunately I am working with 1/4 inch MDF and the largest sheets I could get my hands are at 2' x 4' meaning that I'm going to have one wall with four different 4 foot boards attaching and 4 seams to deal with. Not ideal but I can't find longer strips of 1/4 inch MDF or wood


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## ryansdiydad (Aug 16, 2015)

I see you are in long island.. there are lumber stores there.. You should go to one of them and talk to them. They have to have or can get your a better option than 2x4 sheets of MDF.

Assuming you have a table saw to cut the MDF? Get yourself some 1x Poplar and use you table saw to cut it down to 1/4" if thats would you want.. 

I would consider some alternatives to having seams every 4 feet on the baseboard..


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## abrowning (Jun 2, 2008)

harpua728 said:


> Thanks. Unfortunately I am working with 1/4 inch MDF and the largest sheets I could get my hands are at 2' x 4' meaning that I'm going to have one wall with four different 4 foot boards attaching and 4 seams to deal with. Not ideal but I can't find longer strips of 1/4 inch MDF or wood



I'm confused. Long moldings are readily available. Transportation of said moldings could be tough if you don't have a car or don't drive.


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## harpua728 (Jul 13, 2015)

It's a 1/4 inch by 4 inch piece that I'm using. Tough to find that in long pieces.


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## lenaitch (Feb 10, 2014)

Some of the replies might be lost in translation. A mitre joint viewed from the face of the board will look like __|__; when viewed from the edge of the board will look like __\__. I try to avoid joints as much as possible. Any chance you can get longer pieces of 1/4" poplar? Or 1/4" profile mdf trim that has a plain surface the height you want, then trim off the profile (that might be tough - I think the thinnest I have seen is 3/8"). Ideally, joints should be at a stud. I am currently re-doing some baseboard and the trim I have chosen only comes in 8' lengths, so I am putting a full piece in the centre of longer walls so the joints are off to the sides (at studs) and less likely to be visible. So far they have painted up quite nicely.


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## ryansdiydad (Aug 16, 2015)

Go to a legit lumber supplier.. all kind of different sizes of baseboard is available in lengths from 8' to 18'... my lumber place doesn't have anything shorter than 8'


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## woodworkbykirk (Sep 25, 2011)

harpua728 said:


> Thank you. SO that's better than wood fill in your opinion? Should I use that for nail holes as well?


 it will work for both.. its pretty much what every professional painter i have work with uses. the odd time they might use glazing putty for nail holes however it runs the risk of creating flashing in the paint


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## Yodaman (Mar 9, 2015)

harpua728 said:


> It's a 1/4 inch by 4 inch piece that I'm using. Tough to find that in long pieces.


I have never seen 1/4 by 4" mdf basemold. If that is what you want,
you could maybe use 1/4" sheet(s) of 4x8 masonite, rip to 4", sand, prime, and paint.


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## TimPa (Aug 15, 2010)

harpua728 said:


> It's a 1/4 inch by 4 inch piece that I'm using. Tough to find that in long pieces.


 actually there are a number of ways to skin that cat! you will need to visit a lumber supplier or a cabinet shop, not a box store.


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## harpua728 (Jul 13, 2015)

I'm going to go with 1/2 inch thick MDF since I can get those cut to 8 feet pieces. I will be priming all sides and edges. However, do I need to prime the two beveled edges that will form my scarf joint? Or should I simply glue these edges together without priming them first?


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## 123pugsy (Oct 6, 2012)

harpua728 said:


> I'm going to go with 1/2 inch thick MDF since I can get those cut to 8 feet pieces. I will be priming all sides and edges. However, do I need to prime the two beveled edges that will form my scarf joint? Or should I simply glue these edges together without priming them first?


No primer.


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