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Filling MDF

3.9K views 31 replies 15 participants last post by  splinter.picker  
#1 ·
What are you using to fill interior MDF trim? Painted and non painted.

I used to use Crackshot, but can't find it anymore. All the lightweight fillers I've used have sucked. They dry to a powder that just falls out when I do a light sanding.

Even some I've used in the past don't work the same. Just sanded some Red Devil or DAP Platinum, can't remember that has been sitting for months and it is gooey.
 
#5 ·
I’ve been using the 3M small hole repair. Goes on blue, dries white. Sands really easily without falling out. Doesn’t shrink much, but I usually put it on a little heavy anyway.

Doesn’t last that long once the container is opened, so I usually get the small ones. It’s great when it’s fresh, but once it dries up it’s too crumbly to apply nicely

I like MH ReadyPatch too, takes longer to dry but dries a bit harder, plus it shrinks a bit more and the smell bothers some people. So I’ll usually use the 3M stuff for typical paint-grade trim and keep ReadyPatch for built-ins and anything I’m making in the shop
 
#7 ·
#14 ·
Well, it looks like Elmers for the win. Put it on, came back with some 320 around my fingers, channeled Leo and started sanding and whining. Quick and smooth, and dries super quick I'll be hitting it with paint tomorrow. Does it flash very much? I could only find the orangeish stuff. Half are first and second coats needed and a few are just a second coat.

Only issue I don't like, as someone above said, it seems to dry out in the container while using it pretty fast. But as well as it works, it's worth buying more. Does the white color change stuff work as well?

So much better than the lightweight fillers. What is even the point of them?

I also picked up some of the 3M interior filler. I'll try that tomorrow.
 
#26 ·
Well, it looks like Elmers for the win. Put it on, came back with some 320 around my fingers, channeled Leo and started sanding and whining. Quick and smooth, and dries super quick I'll be hitting it with paint tomorrow. Does it flash very much? I could only find the orangeish stuff. Half are first and second coats needed and a few are just a second coat.

Only issue I don't like, as someone above said, it seems to dry out in the container while using it pretty fast. But as well as it works, it's worth buying more. Does the white color change stuff work as well?

So much better than the lightweight fillers. What is even the point of them?

I also picked up some of the 3M interior filler. I'll try that tomorrow.
I don't whine. I listen to heavy metal
 
#15 ·
Painters I worked with would put the elmers in a ziplock bag, tie the top closed and cut the bottom corner to use it like a grout bag. Seemed to work well. I might have to try elmers again, MH isn't what it used to be. I tried SW wood filler and although easy to use it doesn't dry hard and shrinks too much.
 
#21 ·
I'm on a mission. Trying different products. today the lumberyard gave me a tube of Minwax wood filler since they can't get me the Elmers, which they used to carry. They weren't sure how it would work.

It didn't. It is like fine sand. Super gritty, as in you can hear it as you pull it. Who thought that was a good idea? It also won't go in the nail holes. Anybody have any luck with it?
 
#24 ·
In lthe last few years I've been a fan of MH Readypatch. Seams to go a long ways, dries quickly, easily sands and it doesn't harden in the can as fast. So if it's on the shelf for awhile it's usable. I add so denatured alcohol to soften it back up if the can is getting too stiff.

I haven't used it for exterior. But have for nail hole patches on walls, cabinet and trim nails then prime and paint. Tools well. Sands well.

I like bondo products for large things, especially rot holes on exterior. Large areas are easily machines and it's workable in less than an hour. I've used it on interior panels too, red "lead" glazing is good for that.

Over the years I've used minwax, Elmer's , one type in a squeeze tube. Maybe Dap? They all worked but seemed to be a one and done. After a few months bouncing around in the back of the truck or sitting on the shelf they were useless.

How large of a hole are you putting?

I hate how the ready patch hardening on my fingers and knife as I'm using it. But the bag truck would work, if I remember it next time.

The Alcohol was the only thing that easily takes it off my fingers and knife. So that's something I've been using to make it more workable.

Look forward to hearing your findings
 
#28 ·
In lthe last few years I've been a fan of MH Readypatch. Seams to go a long ways, dries quickly, easily sands and it doesn't harden in the can as fast. So if it's on the shelf for awhile it's usable. I add so denatured alcohol to soften it back up if the can is getting too stiff.

I haven't used it for exterior. But have for nail hole patches on walls, cabinet and trim nails then prime and paint. Tools well. Sands well.

I like bondo products for large things, especially rot holes on exterior. Large areas are easily machines and it's workable in less than an hour. I've used it on interior panels too, red "lead" glazing is good for that.

Over the years I've used minwax, Elmer's , one type in a squeeze tube. Maybe Dap? They all worked but seemed to be a one and done. After a few months bouncing around in the back of the truck or sitting on the shelf they were useless.

How large of a hole are you putting?

I hate how the ready patch hardening on my fingers and knife as I'm using it. But the bag truck would work, if I remember it next time.

The Alcohol was the only thing that easily takes it off my fingers and knife. So that's something I've been using to make it more workable.

Look forward to hearing your findings
I used it to fill trim head screws on my window/door trim and 50%+ holes popped within a few years. The filler is still there, but you can see where each screw is. I recently replaced the rest of my windows and countersunk screws with plugs this time. I still need to get around to fixing the ones with ready patch...next year. This is in NE, so four season climate.

 
#27 ·
Image


These are great for holes. Fill them any way you want ( I use readypatch mostly ).
You can trim the tip for finish nails. Much cleaner especially on prefinished. Fill the holes a little proud and when done I go back and wipe the trim with a damp sponge.
It may seem silly, but, there is less smear on the finish.
10$ for 12 on amazon
 
#31 ·
I wouldn't use Ready Patch on exteriors. Bondo or caulk. Or other plastic filler. Old time painters used a putty similar #33 glazing compound.

Bondo for large holes and rot repair.

Plugs are good. I' m using them with PVC boards and trim. Use the Fasten master when I can.
Putty is what I used back in the day but I mixed it with sawdust, I kept sawdust with me in a baggie because it was too damn sticky.