OT -- drywall repair

[Gramps' shop]

Any reason not to use my ROS to smooth out the joint compound on a small -- 12x10 -- drywall repair?

[-MIKE-]

The risk of sanding too deep. It would *very* easy to sand too far with a ROS without a lot of practice.

That size repair with those black, mesh drywall sheets could be done in less time than it would take to unwrap the get the ROS out, unwrap the cord and plug it in. :-) Seriously, drywall mud is about the fastest thing in the world to sand.

[Gramps' shop]

Thanks, Mike. I think I know where my sanding block is :-)

[ChairMan]

try a damp sponge, too.....less dust

[Bill]

I used 150 grit (screen) on the setting/taping coat, and 220 grit on the final coat with good results. Important to go in a circular pattern to avoid leaving grooves. I've seen others complain that the screens leave defects (before painting), but I think they must not have used a good primer. My experience is limited to one 600 square foot project. If you can spend a little for a sanding pad you can attach to a shop vac, you would enjoy it very much--but you don't have that much to do (maybe you can borrow one?) As suggested, "wet sanding" may be even better (for the last of it).

Bill

[Markem]

A bucket of water and a sponge is fast, easy and cleaner.

Mark

[Leon]

Actually I have done similar repairs but used a finish sander with very good results.

[Leon]

Does that work after the mud has dried?

[Gramps' shop]

Took me longer to attach the paper to the block than it did to do the actual sanding. Looks good ... now the paint.

[ChairMan]

yes

[Markem]

Yes, I use Easy Sand 90 for the first coat, my sponge method if satisfied then I prime, then finishing compound and sponge, prime again.

If I take my time and take off my glasses (being nearsighted in one eye and 20/20 in the other) to inspect you won't see the repair.

Mark

[dadiOH]

Yes, as long as you use drying compound vs setting. The only thing holding the calcium carbonate particles together in drying compound is starch. It melts again easily.

Setting compound is thin gypsum plaster (calcium sulfate); the water causes a chemical bonding and it won't melt after setting.

[Leon]

Hummmmmm, I'll have to remember that the next time our Great Dane or my wife gets excited and knocks a hole in the wall. I had to repair 3 holes in our other home.

[Gordon Shumway]

You better believe It does. It even works with Durabond, too.

In my experience there are two conditions that need to be met to make using a damp sponge more desirable than sanding with a screen, an abrasive pad or sand paper. The first thing is the application of the compound needs to be relatively smooth and the second thing is the sponge cannot be too wet.

If the application of compound was too thick or too inconsistent I use an abrasive and clean up the mess. If the sponge is too wet you will either just smear the compound around or you will take off too much in one area. It takes practice. I've done a lot of drywall repair and replacement and I still prefer to do the majority of the work with an abrasive.

[woodchucker]

Yep, and one more thing, dry wall dust is not like sanding dust. It's much more abrasive, and would probaby destroy your sander (not immediately) but as the dust keeps working at the bearings etc.

I use a dustless system, its a bucket with water, and a hand sander. The dust gets sucked up by the pad into the bucket of water. A shop vac is attached... That's the way to go.

[woodchucker]

yes, but it is not as nice as a sanded finish. you can get wavey results. it all depends on how good you are at scultping, because that is what it amounts to some times... I tried that, not as nice. Acceptable for a few .. much longer than having the right equipment.

[Bill]

I tried using water in the shop vac at first, but the filter clogged. I found that the special "drywall" bags for the shop vac worked perfectly (2 bags for about $15).

[krw]

My thoughts exactly.

I have one that just attaches to a shop vac. As Bill notes, it does plug up but it takes a lot of dust to do it. It's not difficult, though a bit messy, to clean. When the job is done, pitch the filter. Oh, and use the drywall filters. The standard filters are too coarse and the vac will pump the finest dust everywhere. DAMHIK.

The water filter sounds like a good idea, though with pre-mixed mud it must make a real sludgy mess.

[krw]

Premixed mud, sure. Mix-it-yourself stuff contains Plaster of Paris, so not so much.

[woodchucker]

This system is not water in the shop vac, it's a pre-system before the vac. Otherwise you'll just fill the filter with the mud.