Best way to strip paint from old work trailer?

[Tom the Remodeler]

Hello all!

I want to strip old paint and rust from my work trailer. I think the trailer used to be an air compressor or something, but years ago somebody gutted the inside and filled it with metal drawers and compartments. The trailer is constructed of galvanized steel, at least that's what I've been told. There are a number of rusty spots on the trailer, even some places where it has completely rusted through. Here are my criteria:

--- Available tools: I was thinking about using some combination of my RO150 FEQ/CT-22, maybe with some Cristal 40 or Saphir pads, at least for the flat spots. I also own a 4 1/2" angle grinder (fixed-speed, I'm saving for a variable speed Bosch, Metabo or Makita 5"), Which I was thinking of using with wire brushes and scouring pads for the curves and contours. Does anybody have any advise or ideas regarding which tools to use for what?

--- Finished product: This trailer is a work trailer, I'm never ever going to enter it into any beauty pageants. For the spots that are rusted through my intention is to sand as much of the rust away as possible and probably slap some Bondo on them. As for the rest of the trailer, my intention is to spray paint primer the trailer. For a final coat, my thought is to paint it with a gray spray paint, maybe the Rustoleum paint that looks like hammered metal.

So, any thoughts? Any major holes (figurative or literal) you can find in my plans? I look forward to hearing some feedback!

 

[danrush]

Hi Tom,

I know the objective is to keep costs down, (and play with tools on hand),  but I wonder if it might not be an idea to check out having it sandblasted.  That way all the little crevices and grooves will be cleaned out as well.  I took a boat trailer in to a backyard sander a couple of years ago, and got it sanded clean for $100.00.  I have to believe that Chicago is more expensive than up where you are??? 

Just a thought, Dan

 

[nickao]

Sandblasting can make quite a little mess, but is worth it for the results. It is getting cheaper and cheaper to get a nice set up. Here is one of the least expensive I have seen(you need a compressor):

Inexpensive sandblaster with a 5 star rating.

I would like to see how far you can push the Festool sander though.

Nickao

 

[danrush]

I had a little sander like that awhile back.  Sucks lots of air, but works well for small jobs like this.  Maybe sanders for flat work, and sandblasters for tight spots?  You will go through more sand than you think.  Buy way more than you think you need. 

Dan

 

[Tom the Remodeler]

Hi there fellas, thanks so much for the info!

Sandblasting can make quite a little mess, but is worth it for the results. It is getting cheaper and cheaper to get a nice set up. Here is one of the least expensive I have seen(you need a compressor):

Inexpensive sandblaster with a 5 star rating.

I would like to see how far you can push the Festool sander though.

Nickao

Hmm, I'll definitely look into this Nick. I carry two compressors with me, a Thomas Air Pac T-2820ST (5.0 CFM @ 100psi), and a Thomas Air Pac T-617HDN (0.9CFM @ 100psi), though even if I ran them together I'd still be getting only around 6 CFM. It looks like the little sandblaster you linked to draws 9.0 cfm @90psi.... I suppose I could just add another compressor or two (we've got dozens in our shop), or just do it our company parking lot, using our huge shop compressor....... Hmm, you know, this may just work!

I had a little sander like that awhile back.  Sucks lots of air, but works well for small jobs like this.  Maybe sanders for flat work, and sandblasters for tight spots?  You will go through more sand than you think.  Buy way more than you think you need. 

Dan

Roughly how much sand do you think I'd need? Also, which grit of paper would I have good luck with?

 

[nickao]

Look into the blasters that shoot corn meal and other things that may be simpler to clean and possibly less destructive if nec.

I read somewhere you can just suck up the mess and reuse. I am not sure if you have to strain the remnants or not or whether that is for just the corn meal or not.

Nickao

 

[Michael Kellough]

I had a little sander like that awhile back.  Sucks lots of air, but works well for small jobs like this.  Maybe sanders for flat work, and sandblasters for tight spots?  You will go through more sand than you think.  Buy way more than you think you need. 

Dan

Very good advice. You'll waste a lot of material blasting flat surfaces and get irregular results. Blasting thin metal with blunt heavy stuff like sand will case harden and distort/expand the surface and you'll get rippling. This won't show up on corners but don't do it on the big flat areas. Machine sand there. For heavy encrustation's of rust a right angle grinder is the first stage.

Save the blasting for the pitted areas. Best results blasting thin metal are achieved with aluminum oxide media (100 grit is good) followed by the primer. Tent all around with plastic sheeting so you can recover and reuse the media.

 

[danrush]

I should have also said to get way more air than you think you need.  Compressors never seem to put out the air they claim, and you will see it in a drop-off in production in the delivery of abrasive.  Without constant pressure the sand will tend to "bounce"  off of the target as opposed to "cutting " the area to be cleaned. 
Sorry, I don't have the technical terms down, but I hope you know what I mean.

Just a thought, Dan

 

[Tom the Remodeler]

I should have also said to get way more air than you think you need.  Compressors never seem to put out the air they claim, and you will see it in a drop-off in production in the delivery of abrasive.  Without constant pressure the sand will tend to "bounce"  off of the target as opposed to "cutting " the area to be cleaned. 
Sorry, I don't have the technical terms down, but I hope you know what I mean.

Just a thought, Dan

I think some people get confused between "displaced cfm" vs. "continuous cfm". It is my understanding that displaced cfm refers to how much cfm the air stored in the tank can deliver, and the continuous cfm refers to how much cfm the air compressor motor and pump can deliver. So, if you have a large tank, your displaced cfm will often be relatively high, like maybe 15cfm, but once the motor has to kick in to replace the air the cfm drops down into the 2-5 cfm range. One way around this I've seen for on-site work is guys will mate a 2 hp 4 gallon compressor with a 11 gallon hand-carry tank. This gives them increased displaced cfm, and they just have to wait for the tanks to refill. Probably not a good option for sand blasting, but it seems to work reasonably well for spray-texturing ceilings....

 

[ericbuggeln]

Tom, I have had great results with Rustoleum products on metals.  Oil based with primer mixed in looks good with one coat and sparkling with two.

You love buying tools, you should buy Nickaos suggestion and let us know how it works.

 

[Grinding One]

Never,no never put product back thru sandblaster nozzles ,the metal taken off will eat out the nozzle....You`ll be buying more spray equipment if you do.I removed rust from tools with my gun,also 4 coats of paint from old chairs...it works good as long as you keep moving the guns.Also use the recommended grit for the nozzle your using.after your thru blasting head for the body shop parts center and pickup some metal prep,then wipe it down with it and tack it and put your final finish on it.

 

[Dave Ronyak]

I have stripped paint and rust from several cars and trucks using both siphon and pressure style sandblasting equipment with a 1 1/2  - 2 HP compressor that produced ~7 SCFM at 90 PSI.  More pressure and more SCFM output are definitely better.  And a pressure style blaster is much more effective than a siphon style blaster operating off the same compressor.  The particles being blasted are much more effectively accelerated with a pressure blaster.  Here is a URL for a pressure blaster. http://www.eastwoodco.com/shopping/...T&iMainCat=1342&iSubCat=1394&iProductID=15245

I've had no problems recycling the sand.  I start with high quality, clean, dry (very important to prevent clogging) sand and sift used sand through a fine mesh screen before reuse.

The warnings about distortion of flat panels made of thin metal are good advice.  (I once worked for Pangborn who made commercial numerically controlled blast cleaning an bending equipment that used metal shot that could strip clean the entire insides of a RR hopper car in a few minutes or bend the skin of an airplane wing to a precisely controlled compound curve.  Amazing to watch and a good lesson of what shot blasting can do.) 

If you decide to do blast cleaning yourself, be sure to wear proper protection.  You don't want to breathe the dust - risk of silicosis.  I'd pay someone to do the job if you can.

As an alternative, you might consider removing any loose rust and scale using your Festool (Rotex or RAS 115) sander, or an angle grinder with a wire wheel, or perhaps better those scrunge or rubberized abrasive wheels designed for paint removal.  Such products are available from Eastwood Company.    Seehttp://search.eastwoodco.com/search?p=Q&ts=custom&w=rust+removal&Search.x=32&Search.y=11.  And then treating the rusted areas to prevent further rusting.  Seehttp://www.eastwoodco.com/jump.jsp?itemType=CATEGORY&itemID=372.  Wurth also makes an excellent rust conversion product over which you can apply Bondo and paint.  I've found the chemcial converters very effective in preventing recurrence of rust on my cars.

Dave R.