Sandblasting is indeed a quick and effective means to remove rust and old paint to bare metal, but you must be careful not to overdo both the size and sharpness of the grit and air pressure. If you don't have a small air compressor with an adjustable pressure valve, this would be a good excuse to buy one and you will find endles uses for it after you are done with your GH project.

The pro lined up those pieces to avoid wasting grit and yes, lining them up to allow you to sweep back and forth while getting a lot covered with each pass, while avoiding too much in any one spot as you would with spray paint is how to do it. Then, after you are done, or think you are, go back and catch any spots missed during the mass application.

Sandblasting grit comes in many types and sizes, from pricey silicone beads used in auto body work, to plain sand, available at any garden center, but for your your application, just plain fine sand should be sufficient. However, it's important to use only CLEAN sand and for that, the kind sold in bags for children's sandboxes may be your best bet.

To prevent wasting grit, go over the rusted parts with a steel brush to remove as much of the large or loose bits as you can before you start sandblasting, then blow it all off with air, so you can see the spots requiring the most blasting. Repeat compressed air only and a close look between each sandblasting application and you won't miss a single spot.

BTW: If the GH walls are chambered polycarbonate and have any debris in them, an air compressor is the easiest and quickest tool for clearing them before they are resealed on the ends. Compressed air is also a great way to remove any dust that has drifted down and settled onto dry to the touch painted surfaces between coats.

You can also make your finishing job a lot easier, faster and result in superior results by adding a paint gun to your compressor assessories and if you are able to spend a bit more and want to have those steel pieces look as good as possible, to hold up in weather and water as long as possible, bypass Rustoleum and use auto primer and paint, followed by clearcoat. For ease of application and lasting appearance, the latest in acrylic automotive paint really is superior to anything you will find in the paint dept. at a home center and unlike oil enamel, doesn't need baking to develop that rock hard surface; just the patience to give it time to completely cure from paint to clearcoat.

How nice for you, to be able to paint the metal structure of your GH any color you want: Perhaps to match and/or compliment your home?

Oh, yes: You didn't say how badly rusted any piece is, but after you clean off the last speck of rust, if you find metal that has been eaten away and want to fill it in, borrow another page from the auto body shops: Bondo, available at any auto store.

Dear Birdwidow...
THAT was a great response, answered about all my questions. I sure do appreciate the concise information! One last question...in buying the compressor which I know not a thing about...do you have any suggestions as to the "size" or "power?" of it? I love the idea about the auto paint, too! Brilliant!!* Danka.
Brandi

Brandi,

I'm no expert on compressors. I know how to use what they produce and am forever finding new applications, from filling a small portable tank to carry down to the laundry room and blow out the lint stuck in the dryer hose, to clearing the drain holes under the windshield of my car or blasting every speck of dust out of my computer, then just refilling the tank from my husband's big unit.

I did find a website that seems to be pretty instructive for choosing a compressor though. The link is below. Hopefully it will give you good guidance.

I do know however, that air compressors are available in a wide range of sizes and powers and one rule of thumb holds:

You can turn it down if you don't need all of it's power for a particular application but can't get any more out of it than it has to give.

http://www.aircompressorsdirect.com/comparingcompressors.php

Then, start googling. I'll bet you will come up with many articles and critiques on different models and brands and end up knowing a lot more about them than I do.