What is the best tool to sand the roof?

[minty]

The roof of my 1991 International Thomas skoolie is in need of repainting. It has a lot of flaking or missing paint and sadly some rust. What is the best method or tool for sanding the old paint off? I have a small hand sander but I bet that would take forever. Should I rent a sand blaster or is that not the right tool?

[rossvtaylor]

Hi Minty,

Sand blasting is great for thick metal parts...we have one we use for wheels and other heavy things...but it can warp sheet metal and body panels.

If you were talking about the side of the bus, which might be more important to have smooth, I'd definitely stick with smaller hand (random orbital) sanders so you get a better finish. But for the top of the bus, especially if you'e going to use Tropi Cool or some other roof coating, I'd use an angle grinder with a paint stripping disc like this one:



I've not found a difference in brand performance, so just look for something like this at your local home center or hardware store. At our Home Depot, these aren't near the paint section...they are over in tools, near the belt sanders and grinders.

They do make these stripping discs with a shaft, which you can use in a drill, but that will be a much slower process. If you don't have an angle grinder, it's worth getting one for this and many other tasks.

[cadillackid]

I cleaned my roof with strong solution of dawn platinum and water.. went over it twice with that... then used an electric palm sander with 180 grit pre-cut sanding sheets.. changed out my sheet often.. I wernt through a LOT of sheets but i didnt want to mess with cleaning out clogged paper or screens.. it was worth the expense to wipe out a couple of home depot stores of 180 pre-cut sanding sheets.. I hit the worst areas hardest, peeling paint areas were sanded out the farthest.. it moved pretty fast.. i was using my Rigid Corded palm sander.. i didnt "sand down" the bus, I just wanted to rough up the main areas and also to indeed sand down the areas where paint was flaking.. I ripped up a couple sheets around rivets but that was expected..



after the sanding I washed the whole thing down with Mineral spirits.. set it in the sun to dry then rolled on rustoleum pro.. mind you that bus is already a lot of errant paint issues and so I knew it would never be perfect... so uneven areas where I sanded deeper than others didnt bother me.. I put 2 coats of rustoleum pro white gloss on it and it does its job.. that bus doesnt get driven in the elements much so i wont have a good gauge of durability..

[Danjo]

I would not use a sand blaster. Far too aggressive. You’d have to do a blast mask on the perimeter and it’ll be a mess.

I’ve used both paint stripping disk for angle grinder and random orbital sander on the bus and then I used paint stripping disks extensively on some large expanses of textured aluminum siding.

The paint stripping disks are pretty aggressive and require a light touch on smooth aluminum. They do, however, move a lot of material fast. The disks are also a little expensive at about $9. You’d get around 12sqft out of one on smooth aluminum.

An orbital sander is much less aggressive. It will take a little longer, but you’ll get a more uniform finish on smooth aluminum. It’s also cheaper. The 1/4 sheet (square) sanders will allow more choice of paper, but you’ll have to spend time making 1/4 sheets. The hook and loop round sanders are very convenient, but I think you’ll always run dry with an electric model. I’d try some 320 grit wet or dry (dry) first.

The washing part that Cadillackid mentioned is also an important first step. A scotch bright pad and dish soap is a good way to go.

I’d say all should be used.

Wash. Use the sander. Use the stripping disk to get the stubborn spots, go over those again with the sander. Prime with rustoleum primer and paint with rustoleum.

[Danjo]

Originally Posted by Danjo

I would not use a sand blaster. Far too aggressive. You’d have to do a blast mask on the perimeter and it’ll be a mess.

I’ve used both paint stripping disk for angle grinder and random orbital sander on the bus and then I used paint stripping disks extensively on some large expanses of textured aluminum siding.

The paint stripping disks are pretty aggressive and require a light touch on smooth aluminum. They do, however, move a lot of material fast. The disks are also a little expensive at about $9. You’d get around 12sqft out of one on smooth aluminum.

An orbital sander is much less aggressive. It will take a little longer, but you’ll get a more uniform finish on smooth aluminum. It’s also cheaper. The 1/4 sheet (square) sanders will allow more choice of paper, but you’ll have to spend time making 1/4 sheets. The hook and loop round sanders are very convenient, but I think you’ll always run dry with an electric model. I’d try some 320 grit wet or dry (dry) first.

The washing part that Cadillackid mentioned is also an important first step. A scotch bright pad and dish soap is a good way to go.

I’d say all should be used.

Wash. Use the sander. Use the stripping disk to get the stubborn spots, go over those again with the sander. Prime with rustoleum primer and paint with rustoleum.

Edit: For some reason I always think everyone’s bus has an aluminum skin. If you have a steel bus, I’d go with the stripping disk on the angle grinder. Proceed with caution anyway.

[sportyrick]

An angle grinder with a cupped wire brush is pretty good also, but don't get it caught in your clothing or "urgent care here we come".

[cadillackid]

I paint or sand or grind only in long pants and long sleeves

[Booyah45828]

I'm in a similar situation. We've got an enclosed trailer who's roof is starting to rust. The bus could also use a paint job as the 8 year old rustoleum is a little lackluster.

Body shops use DA sanders, use whatever grit you need for the material, and they work pretty well. A grinder with a wire wheel would work quickly to, but might not leave a good finish to paint over.

But, I stumbled upon these kits that adapt your pressure washer into a siphon style wet blaster. With the water, I don't think panel warpage would be an issue, and it also solves the dust issue too. So if you've got a pressure washer, I'd look into trying that. I know I'll be keeping an eye out for one at my local hardware store.

[cadillackid]

Originally Posted by Booyah45828

I'm in a similar situation. We've got an enclosed trailer who's roof is starting to rust. The bus could also use a paint job as the 8 year old rustoleum is a little lackluster.

Body shops use DA sanders, use whatever grit you need for the material, and they work pretty well. A grinder with a wire wheel would work quickly to, but might not leave a good finish to paint over.

But, I stumbled upon these kits that adapt your pressure washer into a siphon style wet blaster. With the water, I don't think panel warpage would be an issue, and it also solves the dust issue too. So if you've got a pressure washer, I'd look into trying that. I know I'll be keeping an eye out for one at my local hardware store.

is this a way to media blast with water essentially? meaning I can rip paint off without huge dust clouds? where does the paint go? in a big ball of goo on the ground?

[Booyah45828]

Originally Posted by cadillackid

is this a way to media blast with water essentially? meaning I can rip paint off without huge dust clouds? where does the paint go? in a big ball of goo on the ground?

I believe so. Paint would turn into dust no different then a dry cabinet, but with the water the powder might turn into goo. No big deal if you ask me, as the paint has to go somewhere once removed. Once I find one and try it out, I'll let you know.

[Bacenures]

https://www.youtube.com/watch?v=wHjp4O8keqc&t=3410s

[rgjarrell]

Speaking of the TV car shows they have ads for dustless blasting system advertised all the time.

You could look into hiring a person near you that owns a system.

An angle grinder will take all day or more. But is effective eventually.

I guess it depends on budget.

Sandblasting either wet or dry is meant to get rid of rust and paint.

Start cheap and see how much progress you make. If it's not working out then you can step it up to more expensive solutions.

[Danjo]

Originally Posted by rgjarrell

Speaking of the TV car shows they have ads for dustless blasting system advertised all the time.

You could look into hiring a person near you that owns a system.

An angle grinder will take all day or more. But is effective eventually.

I guess it depends on budget.

Sandblasting either wet or dry is meant to get rid of rust and paint.

Start cheap and see how much progress you make. If it's not working out then you can step it up to more expensive solutions.

I removed peeling paint from wood-textured aluminum shiplap siding. With the paint stripper disk I was able to do about 20 sq feet an hour.
Seems like any blasting is a big mess and requires masking what you don’t want blasting

[BarnYardCamp]

Be careful if you use a high pressure water system (power wash). You don't want to blast the seams as you could inadvertently cause some leaks. I'd be inclined to use the angle grinder with the strip-disk. Get the loose paint off, scuff up the rest so the new paint has something to cling to and paint it. So what if it's not perfect, no one can see it..it's all about function.

[mmoore6856]

water blasting (power washer +fine sand) is another way and has no dust. you can buy adapters that go on a power washer and convert. i found out about this after i did mine by using a truck (stiff bristled ) brush, a garden hose , trailer cleaning acid in a sprayer, dish soap and sand blasting sand. it worked really good and cleaned the seams and around the rivets. it took my loose paint off too. i finished with a power rinse then painted