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Q: How do I strip/remove an applied coating?
A: Due to the nature of our products, most of our coatings are formulated to be as durable and chemical resistant as possible. Unfortunately, this also makes them very difficult to remove once the coatings have been applied.
If an oven cured coating has been applied, but not baked, then the coating should easily be removed by simply soaking the part(s) in solvent (the same solvent used for dilution will normally soften the coating). If you are unsure of which solvent to use, please contact the Everlube Products Technical Department for further recommendations. In most cases, air-drying products may also be removed using solvent, if the coating removal is attempted shortly after processing. Once an air-drying coating has fully cured, solvent will (generally) no longer remove the coating.
The following methods may used to remove/strip a fully cured coating (oven cured or air-drying):
Grit Blasting or Vapor Honing The first rule of coating removal is this: The Grit Blaster is your friend! Whenever possible, the easiest, safest, and most effective method of coating removal is to simply blast the coating away. If you are going to be reapplying a coating, this will also pretreat the part for the next coating application. This can be done using 200 - 400 grit (or finer) aluminum oxide at 30-50 psi blast pressure. For delicate substrates, other blast media may be used, such as, glass beads, walnut shells, plastic pellets, or even baking soda. For substrates that cannot tolerate any physical abrasion, then one of the other listed methods should be attempted. If your parts will allow you to remove the coating using one of these blast methods, then I highly suggest that you stop reading now and use that method. It only gets worse from here.
Industrial Paint Strippers There are hundreds of paint strippers on the market that may work great for you. Unfortunately, Everlube Products does not have any specific recommendations. Our experimentation with paint strippers has always ended with mixed results. Our experience indicates that paint strippers containing methylene chloride, or those that are phenol based, have the best chance at success. These seem to be the most aggressive. Companies like Chemetall-Oakite, Turco, and Henkel sell a variety of industrial paint strippers that may work for you. Note: Chlorinated paint strippers are not recommended for titanium substrates.
Chromic Acid Solution A 20% - 30% (by weight) chromic acid bath at a temperature of 200oF (93oC) will remove just about any coating in a matter of minutes. Unfortunately, it will also remove skin and just about anything else which comes into contact with it. This method is mentioned with considerable hesitation. Due to the hazards associated with (hot) chromic acid, only those individuals who are experienced with this chemical should attempt its use. Not to mention that once you are finished with the chromic acid solution, you now have to properly treat and dispose of the chrome (this solution is virtually pure hexavalent chrome). The nice thing about this method, however, is that the chromic acid solution will completely remove the coating without damaging the substrate.
Sodium Hydroxide/Caustic Solution A strong caustic solution (20% - 30% by weight) at a temperature between 180oF (82oC) and 200oF (93oC) will also usually remove our coatings. Once again, this (hot) solution is very hazardous and should only be attempted by trained personnel using the proper personal protective equipment. This method is not recommended for aluminum substrates or any other substrate that might be harmed by the caustic solution.
Other Things To Try When it comes to stripping coatings, don’t be afraid to be creative. Just because a certain method is not listed here, that doesn’t mean it might not work. Without going into any detail, the following list offers several suggestions that have worked in the right applications:
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Cryogenics : Destroy the coating by freezing it.
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Burn-off Ovens : Destroy the coating by using high heat.
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Sandpaper : simply abrade the coating off (finer mesh sizes will be less aggressive)
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Steel Wool : same principle as using sandpaper.
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Ultrasonic Cleaner with (warm) NMP Solvent : NMP (n-methyl 2-pyrrolidone) is an aggressive solvent with limited health hazards. The aggressive effects of ultrasonics combined with the solvency of NMP have been used successfully for removing some of our coatings.
Now that you’ve read this far, two assumptions can be made. First, you probably can’t grit blast your parts, or second, you just love to read our wonderfully written FAQ’s. On a serious note, every one of these methods has health and safety hazards associated with them. Before attempting any of these methods, be sure to have the appropriate personnel at your facility review the hazards and determine which method is suitable for use in your facility. Be sure to always wear the appropriate personal protective equipment.
Q: What is the recommended dilution procedure?
A: Everlube Products sells most products in both a concentrate and diluted form. Diluted products are already diluted for spray application. Further dilution is rarely required but they can be further diluted if required by the application method or part configuration.
The technical data sheet (TDS) contains all of the required information for diluting concentrated products. A broad range of dilution ratios is provided on the TDS because the optimal dilution ratio depends on the application method and part configuration. As an example, the recommended dilution ratio for spray application of concentrated MoS2 based coatings are generally in the range of 1:2 to 1:3 (product:solvent by volume), while PTFE based products are typically in the range of 1:1 to 1:2.
When using a solvent mixture, the solvents must be pre-blended prior to the addition of the solvent to the coating. As a convenience to our customers, Everlube Products offers a wide range of solvent blends for use with our products.
Solvents should always be added into the coating, preferably while the coating is mixing. See the FAQ for mixing for further information.
When initially establishing the optimal dilution ratio for a new application, it is generally best to add the dilution solvent in small increments. This will allow you to fine-tune the dilution ratio for your application without over-thinning.
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