How to Prep A Stainless Steel Tumbler

First we will cover prepping a stainless tumbler and priming.  Actual painting the tumbler will be two separate write ups.  One article for primed Stainless Steel, and one for Powder Coated Tumblers.

 

I am going to recommend a different primer than I am sure most of you are using and I will discuss why. Is a different primer wrong? Not necessarily. But there is always good better best.

 

We have briefly discussed this previously, so sorry for repeating myself on some aspects of my recommended procedure, but I want to make this as clear and easy to follow as possible.

 

Issues that I have seen following the boards:

  1. Finishes that come off of the cup.

  2. Rusting under the epoxy.

  3. Finish issues caused by contamination's.

 

Lets talk Stainless steel before we start moving forward.

 

  1. There are different grades of Stainless Steel.

                       GRADE CORROSION RESISTANCE STRENGTH LIFE SPAN MAINTENANCE

302        Poor                                        Best              Fair                  Fair

304        Good                                       Best              Best                 Fair

316        Best                                        Good            Excellent        Excellent

17-4       Fair                                         Excellent       Good               Fair

It is commonly thought that Stainless does not rust. Some grades are very corrosion resistant. Some grades are not. Looking at different cup manufacturers info, not one states what grade of stainless. If someone can provide that information, we will add it. I have seen pictures with obvious corrosion on cups though so we have to assume that some (if not all) are using Stainless Steel grades that can corrode.

Stainless Steel is also not the easist metal to put a finish on with proper adhesion.

What is the difference between using paint or,primer/paint combos that most big box stores sell and the primer that I am going to recommend. In a nutshell. Corrosion protection and adhesion. If something happens, the primer that I am recommending will actually sacrifice itself to keep the rust from spreading. Due to it’s chemical makeup, there will also be better adhesion as it has acid to actually bite into the metal. Please note: All paint should be done in a ventilated area using personal protection equipment.

So, back to actual prepping a cup. From step 2 on, it is wise to wear nit-rile type gloves.  This will help to protect YOU, but it will also keep oils from your hands contaminating the cup that you are trying to clean.  Latex gloves will work, but we do not recommend them as people can develop allergies to latex.

  1. Remove any decals or product information stickers. Heating any area with glue will aid in it’s release.

  2. Wash with HOT soap and water. This will remove Water Soluble Contamination's.

  3. Use a solvent cleaner. I recommend using “wax and grease” remover used in the auto body industry. Any Auto Body store will have this. You want to apply the solvent, but very important, you want to remove the solvent before it dries. Acetone can dry very quickly which can defeat the cleaning process. The solvent “lifts” the contamination. Wiping the solvent off and drying removes the contamination. If the solvent dries back onto the cup, the contamination is still on the cup. This will remove Solvent Soluble Contamination’s. Use a lint free cloth to apply and remove the solvent. I use Sontara E-4143 Solvent wips for what it is worth.  There are other brands that will work fine.  Normal paper towels will lint.  Normal paper towels use adhesives to keep the fibers together.  This can leave adhesive behind causing issues.  Solvent wipes should be a spun type lace so that no adhesive is used and they are more lint free.

  4. Sanding the Tumbler. There are many ways to sand and all will get the job done. I used a 3 inch DA sander with 240 grit, 320 grit Wet or Dry Sandpaper, and what we call a scuff pad in the Auto body industry. Overall, I found the adhesion the same from all three. The scuff pad is probably the cheapest in materials, no tools needed, fastest, it can get into indentations and body lines better than the other two. So, I am recommending using a “Red Scuff” Pad. You can use any brand, but I do use a Mirka Scuff Pad PN 18-111-447. They do come in a box of 20. I will put a link below to Amazon if you wish, and I will offer them by the pad on my website as a convenience since they weigh nothing. One pad could easily do 20-30 cups. You could also sandblast, but I think most of you do not have the facilities to do that.

  5. Re-clean with solvent cleaner.

  6. Use a “Tack Rag” to remove any lint or dust. This can be done on any layer that the paint is dry enough to rub. These are available at any Body Shop Supply. I use Sontara Final Tack Cloth E-4141.

  7. Prime the Tumbler. I am recommending a “Self Etch Primer”. Any body shop supply store will have both aerosol and liquid for a paint gun available. I highly recommend U-Pol if you go aerosol. Why? It has Acid in it for corrosion protection, most of the others do not. U-Pol is an excellent European Line of products. They have two colors, Light Gray PN UPO741 (almost white) and Black UPO837. I spray one very light coat, let that flash for a few minutes, and apply a nice 2nd coat to achieve coverage. 10-20 minutes before paint, depending on the temperature and how heavy that you applied the primer.

  8. You can remove any dust nibs by sanding also in the same 10-20 minutes.

  9. If desired, this can be allowed to fully dry. This would enable a bunch of tumblers to be prepped at one time and then allowed to sit until needed. I then recommend a very light sanding with 600-1000 or a “Gray Scuff Pad” Mirka 18-118-448. You do not want to remove the primer.

Prepping in this manner will give us great adhesion to the Stainless Steel Cup. It will also assure that the cup is clean prior to painting to prevent any issues with contamination's.

Pictures of Stainless cups prepped.  Note the top is not finished yet as it is not final tapped off.  I will finish sand when it is tapped off.

 

Scuff Pads used on the Right tumbler.  Red used for Stainless.

 

Red

Gray

 

Solvent Wipes

 

Tack Rags

Upol Self Etch Aerosol

Amazon Link

 

Links to Amazon are an affiliate link.  We will receive a small commision for your purchase.

 

 

 

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