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The Steel Detailer
It is rare that a "typical" industrial paint job doesn't include components that optimally could be sprayed using only one tip. All too often we select one tip that will suit the bulk of the job, or worse, a tip which is a 'tweener". The "tweener" is reference for a tip which isn't optimal for any portion of the job, and may be slightly under par for everything, but won't require changing during the spray operation.

Unless the project involves rapidly curing coatings (such as plural component products), there is no good reason that we shouldn't use the spray tip which is the best suited for a given part of the project. The benefits of proper tip selection include a better finish quality from more accurate and uniform coverage, material cost savings and increased environmental compliance.

For successful coatings the bottom line, is, well, the bottom line. Curious about the impact for cost vs. savings with using proper tip selection, the perfect job offered itself as an opportunity to conduct a real world test.

We used a project of two identical tanks with loose ladders and handrail as a test study, that had a total of 2500 square feet each. The tank would be about 2000 sq/ft of surface area, and the remaining 500 sq/ft was the area for the ladders, handrail, nozzles, etc. At a theoretical coverage rate of 300 square feet per gallon, the anticipated consumption would be a total of about 8.3 gallons for the required DFT.
The same painter completed both projects, but used a single spray tip for the first project, and switched tips to do the smaller work for the second one. The first job was performed using a tip with a 10" fan and a .017" orifice. Total consumption was 11.5 gallons. For the second order the applicator changed to a smaller tip with a 2" fan and a .013" orifice for the ladders, rails and fittings. Consumption dropped to shy of 10 gallons. Spray time was 5 minutes longer because the tips were swapped out about a dozen times. The completed DFT readings were the same on both projects. The savings in product was almost two gallons.

At a cost average of $35.00 per gallon for primer and $50.00 per gallon for top coat, this experiment saved about $170.00 on material cost just for this job. The additional labor to switch tips proved nominal, but the savings on materials proved out at about 13%. Small dollars add up, and the savings over the course of a year will add up to thousands.
When talking about paint application, theoretical coverage is affected by a wide variety of factors - the amount of ventilation, the ambient temperature, spray technique, accessibility of surfaces, blast profile depth and the spray tips that are used.
Theoretical Coverage
The EPA and local clean air agencies place stringent regulations on emissions. The ability to complete the same amount of work while accruing less emissions can be of great benefit.

Clean air operating permits are typically sold based on volume of emissions. In the typical "Medium Quantity Generator" category, the air permit will cost about $5,000. If the quantity of material processed increases consumption into the "Medium" category, the operating permit doubles. For the "Large" category, the fee jumps to $25,000.

Staying in the lowest possible category not only helps to save cash, but environmental impacts are kept at a minimum.
Tips on Tip Selection
The Painter's Bucket
Environmental Benefits
Press for Success
The point of view for most applicators is that the recipe for success is to finish the job as quickly as possible by using only one tip.

Using the proper tips for the items to be coated allows for ease in application and provides a uniform build, creating a quality finish.

Over time, using the correct spray tip for the job becomes second nature, and the "new" way will become the "right" way.