Soda compared to Sand
The Difference between Soda and Sand blasting
On the left side fine sand is used.
Sand will leave a rough surface behind but better rust removal.
On the right side Soda is used.
Soda will leave a smooth surface behind but will only remove superficial rust.
If desired we can use a mix of Soda and Sand or any other media, blasting wet or dry.
With our Soda Blasting equipment, we can blast with finer sand than a regular machine, The sand on the left which we use is 0.1 till 0.5 mm while the sand on the right used in a regular machine is 0.5 till 1.2 mm. This makes a big difference in the roughness.
Why use Soda
"After all," you might be thinking, "I just want to strip some paint/light surface rust/grease/bacteria/mold/smoke from this project."
To get a good idea of why soda blasting is so good, it might help to understand a bit about how the action of soda blasting is different from other types of blasting. To understand how it is different lets take a look at sand blasting.
We want to remove paint from a fender, let's look at a simplified version of the structure of what we are cleaning. There's not too much to it. You have the metal coated with a layer of paint, in this case, red paint. The paint is thin-thin, only 7 thousandths of an inch thick.
Let's pretend we are going to remove the paint by Sand Blasting. Think about it from the perspective of the paint. That's right we are going to project rocks that are 3 times larger than the thickness of the paint at the fender at a high velocity. The sand is denser than the paint too. The force of the impact smashes and chops through the paint. The sand is harder than the metal as well. Any of the impact force that was not dissipated by the paint is now whacking the metal. Remember this is a thick, steady stream of sand. There is a lot of sand battering the bare metal and the surface ends up pitted and rough. The metal is stripped bare with only a dusting of the pulverized sand covering it's scarred surface. Within hours, the ambient moisture in the air will begin to attack the metal and the process of oxidation (rust) will begin.
I tell you, the thought of doing that to my fender is scarier than a Stephen King Movie. Imagine what would be happening to my poor fender if it were made of glass or wood or brick!
Now let's take a look at what happens when I strip the paint with Soda Blasting.
A crystal of our blast media is huge compared to the layer of paint. But sodium bicarbonate is much softer and less dense than sand but it is still a bit harder than the paint so it can penetrate the paint layer just a bit and this is when the magic happens. Baking soda has a property called "high friability" - do you remember that kid in your grade school class that would go all to pieces laughing any time someone made a joke about flatulence? Sodium bicarbonate is just like that. It loves to go to pieces, that's what friability is. The bicarbonate crystal gets a little into the paint and breaks up. But it doesn't just crumble, it explodes! All of the energy that was projecting the Soda at the paint is released outward and all of the bits and pieces of the crystal are carried along. ripping and shredding into the paint. But, still, the metal is harder than the soda. It isn't affected at all by that battle going on at it's surface. What else is harder than Sodium Bicarbonate? glass, plastic, chrome, rubber, gaskets. Let's face is, Sodium Bicarbonate is that hardest-working wimp you will ever have the pleasure to work with!
When it's all done and my fender is clean there is an additional benefit to soda blasting. The bare, smooth metal has a light dusting of Sodium Bicarbonate. The dust is alkaline. For rust to form there needs to be a slightly acidic pH. The alkalinity neutralizes any acidic component of the air and protects the metal! Pretty cool, huh? Soda Blasting has the same effect when cleaning off mold damage. Molds, and bacteria too, need an acidic environment to survive. When you soda blast you are creating a safe, sterile surface. Still - I'm not going to eat lunch off of my fender!
With my fender stripped of paint, I can now clean and remove any contaminates and paint it a new color. The dust from the soda blasting can be rinsed off, it will dissolve in water. If there are any bits stuck in crevasses, they too will dissolve and rinse away. If I had sand blasted, I would have to rinse and wipe and wipe and rinse. I would have to take extra care to make sure there was no grit left in any crevasses. Imagine all of that uncomfortable grit left over from sand blasting. little bits grinding into your floor, in the seams of your clothing, stuck between your teeth. When it comes to final clean up, Baking Soda being water soluble is a blessing. You can only get so much with a broom, being able to easily rinse away any remaining dust is a huge time saver!
Cleaning anything with soda blasting is a vastly superior process. You can easily remove carbon, grease, oils, gasket material, surface corrosion, paint and coatings from a variety of alloys, plastics and composites without substrate damage or distortion, and leave hard anodized coatings intact.
When you are soda blasting you are saving time by cleaning, degreasing and depainting all in one step. What better paint preparation could there be?