# Does stain ever actually dry?



## KillaVolt (Mar 16, 2014)

Hello all, I'm new to the forum, but just had a quick question about stain.

I'm adding some shelves to a work desk using 1/2" MDF, and wanted to have them black to match the desk.

All I had available was some black stain and urethane.

I've put multiple coats on the MDF to achieve a solid colour and at this point after the last coat it has been drying for 48 hours, plus I've baked it in an oven around 250*F for a couple of hours and the stain still seems to be wet/tacky.

I know stain contains oils, so does that mean it will never truly dry? I'll need to sand it smooth to finish it with the urethane because their appears to be some dust/marks in the stain.

If I apply urethane now, will it dry to a hard finish?

This doesn't need to be flawless as it is just for an electronics work desk, nothing fancy.


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## SkySkrape (Oct 8, 2013)

KillaVolt I'm definitely not the resident expert in finishing...but the MDF caught my attention. I have never heard of anyone staining MDF and I think that has something to do with it. MDF is basically made of pressed sawdust, glue, and probably other chemicals. So it's not solid wood. This would make me think that the stain would sit on the surface and not be fully drawn into the wood like it needs to be. 

One question, did you apply a layer of stain and then leave it? Or did you apply, wait five minutes, then wipe off the rest? That's how you should apply it on wood...otherwise you end up with a gooey sticky layer of oily stain that won't absorb. 

Don't apply poly over wet stain...it needs to cure...sometimes it takes several days, even up to a week or two to fully cute depending on several factors. 

Poly won't let the stain underneath dry...as it's basically plastic once it dries. 

I would take off whatever excess stain you can, wait for it to dry completely, spray paint it, cover it with poly, and call it good


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## Fred Hargis (Apr 28, 2012)

Stain simply has binders. While they may vary a little (varnish, linseed oil, both, other stuff) they all dry (actually: cure). So I wonder the same thing as Skyscrape, application methods and the MDF....but also the age of the stains. They can go bad. If the stain has varnish and outlived it's shelf life, putting more varnish on top of it isn't going to help. But it sounds to me like you just have a very thick layer of stain on it, and if true likely needs to be removed. A black acrylic paint may have been an easier approach.


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## KillaVolt (Mar 16, 2014)

MDF is actually very absorbant. When water gets on it, it soaks it up and expands horribly.

Stain doesn't expand/destroy the MDF, but it does soak in pretty well.

So I applied a first coat and waited for it to be soaked in, then applied another few coats in the same fashion.

Those were allowed to dry over night, then I applied more and more coats.

I've done this on pine before to achieve a solid colour and it turned out very nice on an actual real wood.

I seem to be having slightly different results with MDF.


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## Steve Neul (Sep 2, 2011)

You really shouldn't use more than one coat of a oil stain. All you end up doing is saturate the wood with the binder and that is what is taking an extended length of time to dry. With what you were doing it would have been more effective to add more black pigment to the first coat of stain. On successive coats pigment for the most part wipes off. If the color isn't dark enough then a dye stain is a good method of supplimenting the color. You could even have done the job with an alcohol based dye stain and it would have been dry in less than a minute to where the topcoat could be applied. Then unlike oil stain you can use multiple coats if you wish. I use this one, http://www.mohawk-finishing.com/catalog_browse.asp?ictNbr=178

Heating the wood isn't going to help that much forcing oil stain to dry. It would have needed ventilation too. Sometimes heat will just make the wood bleed the stain and bring it to the surface. 

You are right that water makes MDF expand however the small amount of water in a water base stain will just fuzz it a little. That can be smoothed out when the topcoat is applied.


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## KillaVolt (Mar 16, 2014)

Like I said, I just used what was on hand, and I'm not out for perfection.


It looks like the pigment is dry because when I touch it there is no black stain on my finger, but there is an oily residue on top of it all. It isn't sticky either.


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## SkySkrape (Oct 8, 2013)

I agree with the above post (as usual) by Steve Neul


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## Steve Neul (Sep 2, 2011)

KillaVolt said:


> Like I said, I just used what was on hand, and I'm not out for perfection.
> 
> 
> It looks like the pigment is dry because when I touch it there is no black stain on my finger, but there is an oily residue on top of it all. It isn't sticky either.


 It may be just slick from the binder curing. After all the stain is like you mixed pigment with a very thin varnish. You might check to see if it has much of a stain smell but I suspect it is ready to finish. If it still has a strong stain smell you might wait another day to be sure. Without being there I can only guess. Normally a single coat of stain will dry enough to topcoat with a oil based urethane in a few hours.


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## HowardAcheson (Nov 25, 2011)

What exactly is the stain you are using? Is it a Minwax Oil Stain? If so, did you fully follow the directions on the label? You must allow the stain to set on the surface for 15-20 minutes and then wipe off all the excess. Let it dry overnight and do it again. If you do not wipe off the excess the stain will never dry and it will feel oily on the surface. Any finish you put on top will not dry properly either.

With most oil based pigment stain, applying a second coat does not work well. The stain contains a varnish that holds the pigment onto the surface. When this varnish dries, it seals the surface and subsequent coats will not penetrate.


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## KillaVolt (Mar 16, 2014)

Ya it's minwax I'm using, but there was nothing to wipe off after 15 mins. It all gets soaked into the MDF.

Sanding it was kind of difficult, but I wiped it off a bit, sanded it with some 220 which was kind of hard as it's really "pasty" still.

Then by accident I found that if I went over it after sanding with a thin layer of paint thinner I'd been using to clean my brushes, it made a really nice smooth finish.

It actually looks like after it dries their will be a very even looking coat stain finish.

To answer the question above, no it didn't smell like stain so much as just had a linseed oil type smell to it.


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## Steve Neul (Sep 2, 2011)

KillaVolt said:


> Ya it's minwax I'm using, but there was nothing to wipe off after 15 mins. It all gets soaked into the MDF.
> 
> Sanding it was kind of difficult, but I wiped it off a bit, sanded it with some 220 which was kind of hard as it's really "pasty" still.
> 
> ...


If that helped to wipe it down with mineral spirits that's great. I was afraid to suggest that in fear it would lighten the color. Since you have kind of re-freshened the stain with the mineral spirits I would wait until tomorrow before topcoating.


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## KillaVolt (Mar 16, 2014)

I should also mention that I'm only using stain instead of paint because I have no money, and had this stain on hand. If I had money and a place to actually do some painting I would have chosen a black spray paint instead of stain.


So the subject at hand isn't so much about how to stain MDF as it is about finishing what I've already got


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## KillaVolt (Mar 16, 2014)

Steve Neul said:


> If that helped to wipe it down with mineral spirits that's great. I was afraid to suggest that in fear it would lighten the color. Since you have kind of re-freshened the stain with the mineral spirits I would wait until tomorrow before topcoating.



It's not going to be perfect anyway, there is a bunch of dust that keeps ending up on it. But after the application of the thinner it really improved the appearance of the stain.

I'm not sure if it will still be oily, but I'm going to let it dry until tomorrow and see if I can give it a finish coat of poly then.

one piece I did already apply poly to, and subsequently also applied the mineral spirit treatment as well, so I'm curious to see how that piece will turn out.

I have heard of people in the past having good results from mixing a small bit of paint with the poly finish, or applying the poly to paint while it's still very tacky. But this is for paint and not stain.

The only other experience I have with staining was the previously mentioned pine I had stained to a solid color in much the same way as this MDF, and it turned out really well. 
It was a shelf, and I had it for years, never even put poly on it and it held up very well.


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## Steve Neul (Sep 2, 2011)

KillaVolt said:


> It's not going to be perfect anyway, there is a bunch of dust that keeps ending up on it. But after the application of the thinner it really improved the appearance of the stain.
> 
> I'm not sure if it will still be oily, but I'm going to let it dry until tomorrow and see if I can give it a finish coat of poly then.
> 
> ...


In theory you can add oil based paint to oil base poly. Sometimes when you mix different brands it causes a problem but the biggest difference between oil base paint and poly is the pigment. Paint is just a clear coating with pigment added to it. A safer thing to do would be to buy some black pigment from a real paint store and add it to the poly. It's the colorant in their machines they use to make mix different colors of paint. Either way it should be mixed before it is applied.


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## KillaVolt (Mar 16, 2014)

This is definitely an interesting experiment in the staining of MDF.

I've noticed a big difference between the piece that I baked for about 5 hours, and the pieces that were left unbaked.

The baked piece was able to be poly'd yesterday, though still seemingly just a tad bit "pasty" with the stain. 

Today that piece was able to be sanded nicely, without being oily, and clogging up the sanding block, the finish was fairly hard.


The two pieces that were not baked however are still a bit pasty, much like an oil painting after a few days. Still a bit workable.

This is actually kind of nice as I was able to pick out a bunch of hairs. I wiped them off with a cloth which dulled the finish much like sanding it. Then I used a dry foam brush to smooth that all out which worked very very well (again, much like an oil painting) 

I put another coat of poly on the baked piece today, and now I'm baking the remaining two pieces.



Has this all been a huge waste of time?? yes! 
But it's been interesting none the less. As an engineer I'm interested in how it all plays together and what happens under different conditions etc.

But to all you wood workers out there, Respect.


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## HowardAcheson (Nov 25, 2011)

You realize that you must clear coat the stain with a varnish or some other clear coat. Minwax pigment stain is not intended to be a final finish. The stain will be easily damaged and the pigment particles rubbed off unless it has some sort of clear coat to permanently adhere the pigment to the wood surface.

Minwax makes a couple of clear finishes. Their wipe-on poly varnish is easy to use. Be sure to read the label directions carefully.


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## SkySkrape (Oct 8, 2013)

HowardAcheson said:


> You realize that you must clear coat the stain with a varnish or some other clear coat. Minwax pigment stain is not intended to be a final finish. The stain will be easily damaged and the pigment particles rubbed off unless it has some sort of clear coat to permanently adhere the pigment to the wood surface. Minwax makes a couple of clear finishes. Their wipe-on poly varnish is easy to use. Be sure to read the label directions carefully.


I believe KillaVolt mentioned previously that he will be applying poly as a final topcoat...


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## cabinetman (Jul 5, 2007)

HowardAcheson said:


> You must allow the stain to set on the surface for 15-20 minutes and then wipe off all the excess.


I would wipe off the stain after just a few minutes...maybe 2-3 (or less), as 15-20 minutes is too long of a time. I don't need to discuss why one application of oil base stain should be sufficient, and a second application will likely have adhesion problems, as all that has been mentioned repeatedly.








 








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## KillaVolt (Mar 16, 2014)

The finish doesn't look perfect, but it is sealed and the final layer of poly is plenty hard now. It still seems as if a bit of oil or something came through the top but it wipes of easily.

For the people saying to wipe it off after a few mins, this is all fine and good on wood. I don't know if you guys have ever stained MDF but it absorbs the stain almost instantly. After the first application there is nothing to "wipe off". Also when you do that you don't get a solid colour.

Since MDF has no grain I see no reason to let the "wood" show through because it just looks old and faded from the beginning.

This also would have turned out very nicely if I wasn't fighting dust and a bunch of hair, that's the only aspect where this became so difficult, our apartment is a dust trap and we don't have a furnace to filter the air.

it may seem stupid, but in a few months time I can easily sand and refinish the shelves, and when I do it will look flawless.

I just needed shelves up now and done on the cheap. 

I'll post up some pics later today or tomorrow of the actual application of the shelves. Just work shelves so they'll probably get damaged anyway.


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## KillaVolt (Mar 16, 2014)

as a side note, I also discovered something that should have been totally obvious as an engineer to recognize.

Baking the MDF made it shrink slightly.

When I was placing the shelves, (it's a 3 piece shelf) the center piece was snug between the two end pieces and needed sanding before it would fit between them at all.

I should have just baked it instead, when it starts expanding again it would have fit like an over-sized bearing.


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## Steve Neul (Sep 2, 2011)

KillaVolt said:


> The finish doesn't look perfect, but it is sealed and the final layer of poly is plenty hard now. It still seems as if a bit of oil or something came through the top but it wipes of easily.
> 
> For the people saying to wipe it off after a few mins, this is all fine and good on wood. I don't know if you guys have ever stained MDF but it absorbs the stain almost instantly. After the first application there is nothing to "wipe off". Also when you do that you don't get a solid colour.
> 
> ...


The reason it is recommended to wipe the stain off quickly is if any residue of the stain is left on the surface the finish will bond to the residue instead of the wood and peal off. This is also one of the reasons a second coat of stain isn't recommended. Not all Mdf is equal and some brands of stains don't penetrate so easily in MDF so we just have to say wipe it off quickly so there is no residue left on the surface.


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## cabinetman (Jul 5, 2007)

Some people think that MDF is just insect vomit, but it isn't. Along with the wood by-products and paper there is binder (like a glue) that isn't that porous, which presents a surface (unlike solid wood or veneer) to prevent even penetration of stain. Particle board is similar.








 








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## Tony B (Jul 30, 2008)

KillaVolt said:


> as a side note, I also discovered something that should have been totally obvious as an engineer to recognize.
> Baking the MDF made it shrink slightly....


 And has it occurred to you that baking a product could possibly break down its chemical structure? 
Hopefully, you got lucky and the shelves will hold up.


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## KillaVolt (Mar 16, 2014)

Tony B said:


> And has it occurred to you that baking a product could possibly break down its chemical structure?
> Hopefully, you got lucky and the shelves will hold up.



yes, but they use a higher heat to cure the binding agents than what I had in the oven.

That was my big concern from the beginning, so I kept a close eye on the first piece which was also a piece I could have re-cut from the left over wood.

I know the binders aren't porous, but any MDF I've used has always been very absorbent. This isn't my first time using MDF, just my first time staining it.

... and second time staining anything. First time was real wood and it turned out well.


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## KillaVolt (Mar 16, 2014)

Pic of the final product, the wrap around shelf with the oscilloscope on it.

Now I just need to organize the storage boxes somehow


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## cabinetman (Jul 5, 2007)

KillaVolt said:


> Pic of the final product, the wrap around shelf with the oscilloscope on it.
> 
> Now I just need to organize the storage boxes somehow


Looks good in black. I like that custom switch.:yes:








 







.


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## KillaVolt (Mar 16, 2014)

That's the master switch that turns on the light and outlets beside the light. There is another small toggle on the light that turns it on and off separately as long as the master is on.

I'm also adding a 30W LED flex light that I'm building from a scrap flex light. I'm just waiting on some parts to come from China, but I've tested the LED and it is freakin BRIGHT


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