Wet sanding machine experience?

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  #1  
Old 08-25-04, 12:53 PM
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Wet sanding machine experience?

I was walking thru Home Depot this weekend and my eye caught a new wet sanding machine for drywall. I may be doing a lot of drywall work soon and the idea of keeping the dust out of the air is really appealing due to kids and everyone in the house has asmtha. I didn't really look at it because I was so skeptical but I thought I would ask the experts. Do these machines work?
 
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Old 08-26-04, 06:40 AM
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I'm not sure if this is the same but I'll be renting one of these this weekend to do some sanding... I'll let you know how it goes.

P.S. There are also comments at the bottom of the linked page.
 
  #3  
Old 08-26-04, 07:49 AM
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I think the item in the depot is this
http://www.paintstore.com/archives/d...tching/65.html. Never used it but if I did I would keep the wet dry vac out side and check the filter often.
 
  #4  
Old 08-30-04, 06:15 AM
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Thumbs up Semi-Successful Weekend

The weekend was pretty successful. To give you some idea of the amount of sanding that needed to be done we removed approx 900-1000 sq. ft. of wallpaper that was adhered directly to the drywall (no primer or paint), removing the top layer of paper with the wallpaper. Looking back I should have just skim coated the whole wall but hindsight being 20/20 and all.

The unit that I rented at HD (approx $40) was the Porter-Cable one that I linked to in an earlier post. FYI: if you rent later in the day (less than 4 hours before close) they allow you to keep it overnight at the 4 hour rate.

What the tool comes with
The unit comes with the sanding wand, hose to the vacuum, and vacuum (this was a standard PC wet/dry vacuum).
It does not include any sanding disks or extra filters (although they replaced the filter in the vacuum while I was there).

Room Prep
We removed as much as we could from the rooms and taped plastic across open doorways, closed doors, and turned off the HVAC. Prior to sanding I knocked down all the high points on my patches with a 10 in. taping knife. We didn't seal the doors or tape over the HVAC vents.

Observations about using the tool
I purchased five 220 grit disks (about $6 a piece) and ended up using two for approximately 900 sq. ft. (returning the rest). If you damage the edge of a disk it may leave some nasty marks. They're in the process of changing the types of disks from a disk that is pre-mounted to a foam backer (about $6 a piece) to a foam disk (about $5.50) that you attach the disks ($1.50) to. The only reason I went with the more expensive solution was because at the time they didn't have 220 in the paper. I didn't want to go to a lower grit for fear of swirling of the finished wall.

The tool itself is pretty easy to use... hook the hose up, plug everything in and push the on button. There is a speed adjustment that comes in handy occasionally (personally I just ran the thing full steam). It smoothes out the walls beautifully except inside corners, those still have to be done by hand. I put about two inches of water in the bottom of the vacuum to try to keep the amount of dust down; a plus to doing this is that you don't have to be as careful about emptying the vacuum and dust flying everywhere, just pour off the excess water and scrape out the mud. Something I would do different is to put a garbage bag in the vacuum and then put the water in that, making clean up even easier.

The Negative(s)
If you're using your own vacuum this isn't an issue, however, there's a fundamental design problem PC vacuum. If your filter gets clogged you'll start getting a lot of dust not being pulled away from the head of the sander as you would expect. The bad part is when you go to clean the filter, as you're taking the filter out dust will fall and intake to the motor is right next to where you pull the filter, so naturally dust falls into the intake and when you start the vacuum back up you're standing in a cloud of dust.

Recommendations
It's a great tool and I won't sand another room by hand that needs a lot of sanding (unless I actually owned one of these, then I'd use it all the time). There's going to be dust... not anywhere near what you would get by hand just a little (enough to warrant one cleaning in the rooms that you did the work). If you have the ability to buy a water trap or make your own I would suggest it as it'll make clean up easier and save you vacuum.
 
  #5  
Old 08-31-04, 12:20 PM
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Thanks Merlin!

Merlin - Thanks for all the info on the Porter Cable tool, after reading your post I know I will rent it if my local HD has one. The reason I considered using the tool is that I have a lot of seams showing throughout the house but right now I have two big patch jobs and wonder if I need to sand the entire wall or not. I pulled out two A/C wall units and now have to patch them. Should I sand the entire wall smooth and then re-texture or try to match the texture?
 
  #6  
Old 08-31-04, 03:11 PM
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Another option you have is to sand down what you have. With a fine grit paper a shallow wall texture will come right off. If the wall isn't too large I'd go this route, beats always looking at the wall and knowing the texture isn't quite right. Just make sure you feather your edges close to corners when mudding.
 
  #7  
Old 08-31-04, 03:33 PM
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Why not try to match the texture first then get involved with sanding if you must as a last resort. scrape off the texture around where the ac used to be about 4 or 5 ". do the repair and see what it looks like after you patch. It would help to know what kind of texture you have. If it's not light you really don't want to sand it off. Personally I would try to cut out the taped joints that you say are visible with a utility knife. Score on both sides and see if it comes off. if not then try a sharp paint scraper . No dust. I would at least try these options before sanding. Btw when you sand in 1 room put a fan in the window blowing out[ use tape around the fan so no air come back in through the sides of the fan]and leave the door open. The negative air pressure keeps and stray dust mostly in the room you are working in.
 
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