Equipment Vendors



Last Updated:  05-20-14



Plasma Water Tables can present a challenge when it comes to finding the ideal additive for the water.

We are constantly looking for the ideal additive.  One day when we were cleaning some parts with Evapo-rust we got an idea, Could we use it as a Plasma water table additive? We have been using Evapo-rust for several years for general rust removal on restoration parts.  We like Evapo-Rust because it is safe, and biodegradable.  So we don't have to getting into a hazmat suit to use it.  We first found it several years ago at the SEMA show in Las Vegas.  We were immediately interested when we saw the people at the both soaking there hands in it.  For them to do that for basically 4 days of the show it had to be safe.

If Evapo-Rust works so well at removing rust and its safe for skin contact could it be used in a plasma water table to prevent rust?  I contacted the manufacture and asked this question.    They were very helpful and suggested another one of their products called Rust-Block at an option for our plasma water table.  We got a 3 gallon pale of their Super Concentrate Rust-Block sent out to try in our table.

Here is a brief breakdown of what Rust-Block is:

Rust-Block = Rust Inhibitor










We used a product Called GreenCut for the first year of table use.  After that we cleaned out the table and tried Plain water with no additives for one month and will never do that again.  The rust that resulted was horrible.  The slats were the main victim but the splash onto the sheets being cut caused staining and very rapid rust production.    Here are some pictures of the resulting rust.


To get the table ready for the Rust-Block test we needed to start fresh with a clean table so the rusty water was drained and the table was cleaned out.   The slats were cleaned with a wire cup brush to get them as clean as possible.  The ideal situation would be to start with a sterile perfectly clean table but this is the real world and that is not possible all of the time.  Rust-Block is not designed to clean parts but instead keep them from rusting so starting from as clean as possible point will ensure the best results.  Here are some pictures of the table after cleaning it out, and a slat before and after cleaning.

With the table clean it was time to mix up the Rust-Block and add it to the table.  It cam in a 3 gallon super concentrate pail.   Per the manufacture the ideal mix ratio is a concentration of 3.0 to 4.6% measured using a refractometer.   We did not have a refractometer so a quick trip to the web and ebay and we had one on the way for $25. The refractometer is a necessity when it comes to mixing and checking the concentration down the road.  They are inexpensive and easy to use.  Since we were using this product for the first time we tested the PH as well using simple paper ph strips, also available on ebay.

This picture shows our mini lab that we set up for initial testing.  The refractometer is the object in the lower left.  We used distilled water to calibrate the meter before the first use.   The cut has the Rust-Block and the ph paper is in the lower center.

PH paper is not exact but it will give you an idea of where you are at.   We first tested our water and found it to have a ph of 6-7.  The PH of the Rust-Block was 9-10 on the paper.   The manufacture lists the PH as 8.5.  Given the paper is not an exact science we are in the ballpark.   

Rust-Block is listed as water soluble with a specific gravity of 1.02 with water being 1 so a touch heavier than water.   We will do some concentration testing down the road and check for settling and concentration levels at different depths of the water table.  



To ensure that the concentration was correct and the Rust-Block was completely mixed with the water we mixed it in a 5 gallon bucket.   We started with precisely 5 gallons of water then added Rust-Block a little at a time and mixed it toughly and then tested the concentration.   We found that 28 ounces of Rust-Block to 5 gallons of water gave us a concentration of 4% which is within our manufacture recommended range of 3.0 to 4.6%.   It is important that the Rust-Block be toughly mixed with the water so that is why we mixed it in a 5 gallon bucket instead of filling the table with  water and pouring the rust block in.    We used a drywall mud mixer in the drill to mix the liquid and then poured the mix into the table.  

The Rust-Block has an amber color which was apparent in the white bucket but once it was poured into the table it appeared to be completely clear.

There is a slight odor to the mix but nothing overpowering.   Our table took a total of 80 gallons to fill.   We used all 3 gallons of the concentrate to achieve our 4% mix solution.   

Ok if you are doing your math here:   70 gallons = 14 (5 gallon buckets)   28 oz per 5 gallon bucket = 392 oz total,  but 3 gallons = 384 oz so somewhere there are a few ounces more or less.   This gets you in the ballpark for mixing and achieving the correct ratio though.  

During the mixing process I got the mix on my hands, arms, legs, ect,   no burning or irritation was ever felt.  While its never a good idea to expose your unprotected skin to any chemical I did not experience any reaction to the Rust Block.

With the mix complete and everything added to the table you can see that the amber tint is no longer visible.  The bubbles are from some over mixing / aeration on my part.


There are many options available when it comes to additives for your water table.   From commercially available additives to home brews that you can find on the forums and web.   Most of the commercially available options have MSDS sheets with so many warnings and dangers that you feel like you need a hazmat suit to use them.  There are several debates about the cancer causing potential of some of the commercial options as well as the home brew options that you find in the forums.   

The reality is that what ever you use will get on your skin and will be atomized and vaporized during the course of cutting so its imperative that you pick a safe option.  Rust-Block is listed as non-toxic which is a definite selling point.

Rust-Block is not marketed for the Plasma water table market at this time.   This is a test to see how well it performs compared to the options that we have already tried. So let the test begin.  We will be evaluating every aspect of the mix over the next few months including:

Concentration checks with evaporation

PH levels

Affects on painted and powder coated surfaces

Rust protection

Affects on plasma cut performance

Check for settling of product

Checks for affects on aluminum and stainless steel


We would like to get a minimum of a year out of this mix.  We will update our observations of the next few months to keep you updated.

*(Test Start Date:  8-11-13)

For more information on Rust-Block you can visit the Evapo-Rust website:    

How Do we expect it to work?

The idea with using Rust-Block in the plasma table is that it will prevent rust from forming on the slats and table components, and when is gets splashed onto the metal being cut it will deposit a protective coating onto the metal preventing rust from forming.  

What about welding, painting and powder coating of the metal after having this film deposited?  The film is water based and can be simply rinsed off with fresh water.  

We send a lot of our products out for paint and powder and will test this out.

Test update:   12-20-13

We have been using the Rust Block in our table for a few months now and have had mixed results.  

Advantages:   No change in cut quality,   no problems with damage to the power coat finish in the tank, no problems with finishes ie painting, powder coating, anodizing or metal stains and patinas.   No interaction problems with metals tested:  aluminum, stainless steel and aluminum.   No increase in smoke or fumes*  (non scientific testing visual comparison only)  We have also had no problems with skin irritation from contact with the liquid.  Also no eye or lung irritation has been noted during the test.  We did not find any settling of the product over the course of the test.  We found concentrations stayed even throughout the solution.    We also were very pleased to find that while we had significant evaporation during the test it seemed to only be water loss as when we refilled the table, and tested our concentration we were still at a 4% concentration.

Disadvantages noted:   The rust blocking abilities had been under what is expected or have found with the GreenCut test.   We saw no change in rust on the slat surface covered by the solution.  When the solution level lowered we saw increased rust formation on the tops of the slats after extended air exposure.  We did tests with the material scrap left from a cut and placed some on the back corner of the table over the bed and some we stored with our other scrap steel looking for rust formation.   We noted significant rust formation on the pieces left on the table.  Those pieces that were stored indoors in our metal scrap pile showed minimal rust but still we had rust propagation across the service after being exposed to the Rust Block solution.

We also noted an increase in our PH of the solution up to a 12 during the course of the test.

We contacted the manufacture and informed them of the test results and requested a second pale of the concentrate to increase our solution concentration to 8% and retest.

We received the second pail of concentrate same as the first and added it to our table.    This mix brought our concentration to 8% as measured on our refractometer.   

We tested our PH and found after adding the concentrate and filling the table we were at an 11 which is close to baking soda and a household ammonia solution.

For the second phase in this testing we plasma cut several circles out of 20 Gauge mild steel.   The circles were all sandblasted on both sides and dipped into our new solution.    The circles were placed in several locations:   Fully submerged in the tank, sitting on top of the slats and placed in a few places around the shop.  We will evaluate the samples and the solution over the next couple of months and update the information.

The photo above shows the rust/crystaline formation on the top portion of the slats that had formed during the first few months of testing.