Fixing Particle Board That Has Raised Grain Excessively

[Jay Chan]

I have mistakenly applied water-based latex primer on my particle board book case that I am building. Now the areas where I have applied water-based latex primer have raised grain excessively. I have tried sanding the raised grain. But I can only sand away the high spots, and I cannot sand enough to remove the low spots (primer keeps clogging the sand paper doesn't help either).

Yes, I should have used oil based primer. I have applied oil base primer in one small area of the book case, and it turns out very nice after I have sanded the area. But this is too late now because I have already used the water based primer on most of the book case. I cannot turn back the clock, I need to find a way to "fix" the problem.

I can try aggressively sanding the surface. But I am afraid that the sandpaper will keep clogging. And the heat that will generate from aggressive sanding may not be good for the primer.

I can paint several more coats of latex primer, and hope this I will fill up the low spots. But I am afraid that this is just wishful thinking. The primer may simply follow the ups and downs of the surface, and I may just waste my time.

I can use chemical to remove the primer, and do this over again. But I am afraid that the chemical may raise the grain even more.

The only way that I can think of is to use a scrapper to manually remove the primer, sand out the raise grain, and re-prime with oil based primer. But I think this will be the last resolve.

Is there a better way to deal with this problem?

Thanks in advance.

Jay Chan

[Nova]

I'd compare the amount of time and effort necessary to recover from the mistake to the expense of new particle board, plus the time and effort to rebuild a new bookcase.

[Lew Hodgett]

Plan "A": Replace the damaged board.

Plan "B": Replace the damaged board.

It's a tough choice, but there aren't many options.

Lew

[dadiOH]

Because you don't have enough coats. _________________________

There is no reason you can't apply an oil base primer over the latex. No particular reason to but you can. _______________________

Uhhh...that's why you sand between coats...to cut down the ridges. _____________________

1. I seriously doubt that the primer "raised the grain". Particle board is inherently rough; not so much to feel but it has a multiplicity of small hills and valleys. That is true even if you have sanded it thoroughly.
2. The only way to *ever* get a smooth surface is to fill the valleys.
3. The best thing to fill those valleys is sanding surfacer. It is a thick bodied, easy sanding paint meant for the purpose. You apply, let dry and sand until all is flush. It is likely to require multiple coats before you have a baby bottom surface as you may well sand through the initial coat(s). Doubt you'll find a good one at paint or big box stores. You can get it at autobody stores but that is generally lacquer base and will eat latex/oil.
4. Particle board is a terrible choice of material if you want a good paint job.

[Leon]

The problem here is that you do not have "raised grain". Sawdust can no longer have raised grain. What you have is a ruined panel. Time to replace the panel.

Snip

Consider this a lesson learned and start over. Your time is certainly worth more then the material. Keep your water based finish but make your first coat of sealer be shellac.

[Earl Creel]

Jay something you might try before starting over is to give the surface a coat of plain ol sheet rock mud. It sticks to most anything, it dries fairly fast, is easy to apply, can be sanded to a feather edge and is cheap. It does shrink and you may have to apply several coats, sanding between coats. Just go after it much like you would get a sheet rock wall ready to paint. After the mud job give it a coat or two of a good primer ( I have had good luck with Kiltz) Then top coat it with the paint of your choice. Sheet rock mud and paint get along just fine, millions of square feet of wall surface indicate the combination works. Earl Creel

[SWDeveloper]

[Jay Chan]

surfacer, and try it. I guess it is something like the "filler" that Norm used in one the recent woodworking TV show.

When I said I cannot try oil based primer, I meant I don't want to try putting oil based primer over the water based primer. I don't know enough about how different types of primers will interact with each other. Of course if I could start over with, I would definitely put oil based primer on the particle board instead of water based latex primer.

Actually, the particle boards that I have primed with oil based primer (instead of water based primer) turn out very good after I have sanded them. The problem only has to do with particle boards that I have primed using water based latex.

Jay Chan

[Jay Chan]

I have a feeling that your "sawdust" comments are referring to MDF. The particle board that I am talking about have many tiny chips in it. The water based primer has swelled those tiny chips on the surface of the particle board and create large hills and valleys.

The manufacturer has sanded the surface smooth, and it costs less. These are the reasons why I am trying to use it to build a book case. Unfortunately the exposed cut edge tends to be rough, and needs to be banded with a piece of wood. Because of the added time and effort to cover the exposed cut edge of the particle board, I think next time I will use MDF for painted furnitures.

Jay Chan

[Jay Chan]

Thanks for the suggestion of using dry wall compound to fill the low spots on the particle board. I think I will first try the sanding surfacer or filler that another newsgroup member has suggested. If that doesn't work for some reason, I will try the dry wall compound trick.

Jay Chan

[Leon]

You caught me there Jay. My mistake. I was indeed picturing MDF when I read Partical board. As you have witnessed, that too is difficult to deal with, no so much as MDF. Please forgice me.

Oil based on that MDF or prime with shellac.

[GROVER]

If the majority wins, my vote would be to toss the particle board in the dumpster. The material is not the best choice for book cases, to begin with, as it sags over time. Further the stuff is inexpensive when compared to say birch veneer, a much better choice for you application. Also the time needed to rectify exposing the MDF to water is worth more than the material. Joe G

[Jay Chan]

Thanks. Indeed, if I could start this project over with, I would have used solid wood or plywood, or even MDF. But I don't want to start this over because the project is almost done except for putting on a finish. I will apply a coat of filler and sand the surface during this weekend to see if this helps.

Thanks for pointing out that using MDF is like using particle board will have the potential problem of getting water damage (in case the paint comes off in an area of the bookcase and someone leaves a wet rag or a glass of cold water on it). I only thought of the upfront cost, and I didn't think of the "maintenance" issue. OK, I will not be using MDF or particle board for my next project.

Jay Chan

[Steve]

Jay Chan wrote in news: [e-mail]:

You're giving MDF a harsh review. I have used it successfully for several large projects. I've recently made a 9' x 15' multi-section shelf unit and a corner cabinet for a massive HDTV.

I first apply a coat of Kilz and sand it down. Then I put on two or three coats of latex paint, sanding in between and removing dust with a tack rag. I guess I could use the oil-based Kilz, but I never have, because it takes too long to dry, and my wife hates the smell. I haven't had a problem so far.

I'm told that MDF was developed for sign painters. I don't know if that's true, but a good coat of paint on ALL the surfaces will make it pretty much waterproof.

MDF _does_ have other problems, like swelling if you don't pre-drill for your screws.

I agree with you about particle board.

[whit3rd]

There is one possibility that hasn't been raised yet; the particle board is wood fiber held by glue and latex paint into a rough surface. So, get an iron and flatten it. Heat, pressure, rubbing against a flat surface, and it gets smooth again.

I had a bookshelf blow over during assembly (silly me, did the finishing outdoors, and stood up a 6' bookshelf), and the plywood side got a crack. Not too bad structurally, but REALLY ugly. Painted lotsa white glue into the crack (splinters pointing everywhich way- REALLY ugly). Let it dry (but it was still REALLY ugly). Then covered it with aluminum foil and ironed the damage flat. I have to point at it today or no one notices.

[Jay Chan]

that I am building. Now the areas where I have

small area of the book case, and it turns out very nice

I finally fix the problem by doing these: o Applying two coats of oil based primer over the latex primer while making sure that I place the surface horizontally. o Sanding the surface using 100 grit sand paper.

When I sanded the latex primer, I kept having the sand paper clogged. Oddly, this time I don't have this problem when I sand the oil based primer. Not sure if this is a difference between oil based primer or latex based primer, or this is a difference between a new primer and a

1-year old primer.

I still need to touch up and sand some areas that are more troublesome than the rest. But now I can see the end of the tunnel.

Jay Chan

[dadiOH]

I don't recall what your planned topcoat is but you should continue sanding down to at *least* #150 - finer is better - else the scratch marks in the primer will be painfully obvious after you topcoat.

[Jay Chan]

I am planning to spray oil based paint from a can as the finish top coat. I use spray paint from a can mainly for the low price and the fact that I probably don't need to sand the top coat if I spray paint.

I will follow your advice and try finer grit sand paper to sand the surface before putting the finish coat. Thanks for pointing this out.

Jay Chan