Repainting Aluminum, How to Do- RepaintingAluminum.com

Repainting Aluminum in Two Stages


 

Repainting aluminum is a more sophisticated task than repainting common steel. Industrial companies use various highly toxic chemicals that are not suitable for do-it-yourselfers. Yet, several common techniques will help you with the majority of repainting aluminum jobs. Follow them rigorously and make you aluminum surfaces shine again.

 

 

Repainting Aluminum: Pretreatment

 Before repainting aluminum, a suitable pretreatment process is necessary to allow coating to hold. It is very important to cover the whole surface thoroughly and correct any voids. That’s why chromate-containing pretreatment substances have been by far the most popular ones in aluminum jobs for the last 30 to 40 years. They have distinct color (e.g. yellow or brown) and are easy to identify once applied to the surface. Any voids can be easily spotted and corrected accordingly.

 

In certain cases, it may be possible to degrease the surface using common power washers (with soap content) and then rinse with tap water. For smaller aluminum components chemical degreasers are applicable as well. Keep in mind they should be applied only by oil-free sponges. Colorless pretreatment coatings are not as popular in aluminum jobs, simply because they make it hard to tell which parts of the surface have been treated and which remain untouched.

Usually, pretreatment is a complicated task that is done in several stages. Each stage should be performed exactly as described. Two possible pretreatment systems are given below.

 

Pretreatment system #1:

  1. Clean with alkaline cleaner. The exact type of cleaner to be used depends on the type of alloy being processed. Recommended are aluminum-safe and mild etch types.
  2. Rinse with water;
  3. Apply iron phosphate solution (with fluoride). It is necessary for the best paint adhesion;
  4. Rinse with tap water.

 

 

Pretreatment system #2:

  1. Clean with alkaline cleaner;
  2. Rinse with water;
  3. Do caustic etching;
  4. Rinse with water;
  5. Clean with nitric acid desmut;
  6. Rinse with water;
  7. Apply yellow chromate;
  8. Rinse with water;
  9. Rinse with deionized water;
  10. Dry at 70 °C.

 

 

Repainting Aluminum: Applying Paint Coating

After pretreatment, you can proceed with your repainting aluminum job. One of the most effective techniques used in industrial job is called anodizing. Paint coating applied with anodizing is perfectly smooth and lasts for many years, which are exactly the qualities expected from it. Anodizing is a quite complex chemical process that calls for both experience and knowledge when performed.

 

Unfortunately, DIY applications of anodizing are very limited. It is only possible to apply this technique for smaller aluminum components. Also, hazardous acids are used as anodizing solutions, so the job must be performed with extreme caution. If you’ve never attempted this method before it is safer to avoid it unless you have someone experienced by your side to guide you through.

Otherwise, stick to common time-tested methods that are known to produce good results for reasonable money. For instance, roll and tip painting technique produces solid results that are very close to purely industrial finish. It should be performed as follows:

  1. Use quality foam roller to roll the paint in small sections;
  2. Without any interruption take a quality bristle brush (foam brush will do ok, too) and brush at an opposite angle (compared to the first operation). This second layer is essential to create a truly great finish that is hard to achieve otherwise;
  3. Allow curing time recommended by the paint’s manufacturer. The paint will level itself, so don’t attempt any touch ups in the meantime – it will only create marks on the finish;
  4. Afterwards, you can sand the surface a little to level it out and make it perfectly smooth;
  5. Repeat first four steps for 1-2 additional coats. This way you will make you finish nice and solid.

 

color for aliminum

 

After the last coat, let the paint cure completely before making use of the painted alloy component (can take up to 10 days to cure).

 

Repainting aluminum is not an easy job that calls for knowledge and experience with paints and tools. Yet, it can be performed successfully in a DIY environment if you can follow the recommendations listed above.

Comments:

  • Mikero(2013-05-30)

    Good guide for me, thanks guys!