(Question) Finishing Tips for MDF Body

[foot]

Hey all,
I have a Telemaster project I purchased from Zamm a while ago that I'm getting ready to start finishing. Having never worked with MDF before I was hoping someone in the OSGverse would be able to provide some tips to help minimize my almost certain mistakes and set backs. I purchased primer and Dakota Red from Reranch, so I'm going with a solid color (I plan on ordering the clear from them soon in another order). One source I found online said to get the MDF smooth with 600 grit before priming. Does that sound agreeable?
Thanks for any and all help!
-Kevin

[hpr_hpr]

For any wood, the smoother before the finishing starts the 'glossier' the (potential) result.

MDF has it's own challenges . . . if will probably sand quite easily BUT (if the european variety is any guide) it will soak up primer like a sponge.

My recommendation . . . for what it's worth . . . sand it as flat as you can stand (down to 200 at least . . . 600 may be overkill) THEN give it 2 or 3 coats of primer and sand that (starting at where you ended for the bare material) to down to 600 (or even 800), spray color, sand to at least the same grit as before, spray clear and go for the glossy finish.

Use a sanding beam or good level (attach sand paper with painters tape and super glue, you can find the how to on youtube) for the front and back to avoid sanding in any divots. Use a flat sanding block for the convex curves and a rounded for the concave parts - try to avoid using the sandpaper directly in you hand - and be CAREFUL sanding the corners of your work as that's were the primer/paint will be the thinnest and removed the fastest . This works for sanding the primer and color very well . . . superglue and water do not mix however so for the clear were you will do the wet sanding down to 1500 or 2000 it is back to - preferably - a largish block with as flat a bottom as you can find . . . other posters may have an even better idea possibly and once again, the corners are the 'touchiest' with the least covering probably which disappears the fastest.

[sirspens]

Be careful sanding MDF. That F stands for formaldehyde. And the dust is very fine, gets airborne easily, and can be breathed in easily.

Wear a mask. Be safe.

[danbind]

Wouldn't you want to seal MDF before primer? Depends on the primer, I would think.

Also: How do you get hardware to mount securely in MDF? I would think it is too soft for regular wood screws...

[parry]

***NOT AN EXPERT***

But... would it not make sense to seal the surface with a poly (spray?) - lightly wet-sand the poly flat, and then paint?

[sirspens]

Also: How do you get hardware to mount securely in MDF? I would think it is too soft for regular wood screws...

It worked for the Kalamazoo guitars. Though, they are super heavy.

[Mad-Mike]

Just an idea I took from a Youtube video of a guy copying his Teisco Tulip out of plywood.

MDF can be rather capable of soaking up finishing materials, just like multi-layer Plywood can if not properly filled. One trick I saw this guy do is he used a bottle of superglue and then sanded it with fine grit sandpaper to fill in/seal the open layers of wood.

Thinking about it myself, I'm toying with making an MDF guitar eventually as well. Probably an original design based off 60's student models.

[hpr_hpr]

Re: sanding superglue.
>> Please wear a mask and put a dust extraction system on it (aka shopvac in my case). It I'll generate fine dust that's even less healthy than fine wood dust.

Re: poly spray.
>> That would work but when wet sanding be careful NOT to sand through the poly, MDF and water are a terrible mix and the damage is pretty much impossible to fix.

Re: weight of MDF
>> Yep I don't know the specific gravity but it does seem to top almost all solid woods.

Re: F stands for formaldehyde
>> MDF = Medium Density Fiberboard sorry persnickety . . . unless it's really fresh or thick it will have gassed out so that isn't the immediate problem unfortunately the other component in the glue is urea which does NOT gass off and can be quite irritating when breathed as fine dust so the warning to wear a mask stands.

Re: Masks
>> Unless you have a chemical filter mask (and they are pricy) something like formaldehyde gas (or any other gas) will not be stopped . . . don't stop wearing one though, there are plenty of fine particle dusts that as even more harmful than formaldehyde gas.

[sporeleki]

Thank you hpr_hpr for clearing the stupidity.
"F" should stand for fucktard, with all the "facts" some tone monsters banter around here.

BTW - does thin CA glue have better tone than the thick?

[hpr_hpr]

Nope understandable mistake . . . and you got the 'problem' with the glue right.

Interesting bit of Trivia, theWWII era Mosquito fuselage was assembled with the same kind of glue . . .

[hpr_hpr]

BTW - does thin CA glue have better tone than the thick?

Not sure I understand you here, is that a typo? Sorry reread it and now I got it . . .

No I don't think so, the thinning compound is almost certainly volatile (like acetone) that evaporates. The thin type will thus 'shrink' a bit more on drying - and dry just a tad slower -, but it wouldn't take much to make all the difference so in the end I don't think the physical properties of the final material will be all that different.

[danbind]

Nope understandable mistake . . . and you got the 'problem' with the glue right.

Interesting bit of Trivia, theWWII era Mosquito fuselage was assembled with the same kind of glue . . .

Those Mosquitos had terrible sustain...

[hpr_hpr]

Nope understandable mistake . . . and you got the 'problem' with the glue right.

Interesting bit of Trivia, theWWII era Mosquito fuselage was assembled with the same kind of glue . . .

Those Mosquitos had terrible sustain...

But they were beloved by their users nevertheless . . . .

Oh and I might argue that mosquitos have infinite sustain . . . have you ever tried to get one to shut up when you're trying to go to sleep . . . .