Silver Reduction Metallization vs. PVD, Vacuum, Sputtering
What’s the difference between Silver Reduction and Vacuum metallization?
I get this question a lot.The term ‘vacuum’ has become the generic term when talking about metallization. While Vacuum seems to be the common reference when talking about metallization, there are several other similar metallization processes that yield identical results.
Silver Reduction and Vacuum are the most common metallization processes used in packaging today.For the purposes of answering the question, I will group PVD, Vacuum and Sputtering together since the metallization in these 3 processes is accomplished in a vacuum chamber.Silver Reduction, PVD, Vacuum and sputtering; the metallization layer aside, are all very similar processes.
Think of it as several different ways of getting to the same result.
I’ll also address a concurrent question I also get; – “does one metallization process have better adhesion”?
The answer is no.
All processes must be done correctly and when done correctly they will all have similar results and pass tape tests, cross hatch and twist tests identically. Adhesion is a result of a proper primer process and the actual metallization is not a factor.Failure of adhesion = poor primer process, poor surface energy modification and with to respect to the topcoat poor curing of topcoat neither of which have anything to do with the type of metallization.
Silver Reduction is a ‘spray’ process of depositing a shiny metal layer onto a substrate.
PVD, Vacuum, Sputtering use a particle deposition process to deposit a shiny metal layer onto a substrate:
- •Silver Reduction uses Silver as the metal to create a shiny surface
- •PVD, Vacuum, & Sputtering use Aluminum
- •Silver reduction is a continuous production process all the way through
- •PVD, Vacuum & Sputtering are ‘batch’ process in the metallization process then continuous in the topcoat
- •Silver Reduction may perform better when metallizing parts that have gaps or seams (vacuum process may have contamination in the gap or seam area)
- •The Vacuum process is typically better able to metallize geometric and angular parts
- •The different processes yield virtually identical finished results to the naked eye, appearance and visual quality are the same
- •All processes are subject to adhesion failure if the surface tension of the substrate is not properly adjusted and/or ‘primed’ or if the topcoat is not properly cured
- •Improper primer will cause adhesion failure
- •Improper flame treatment will cause adhesion failure and or a brittleness or ‘crisping’ which may lead to part failure
- •All processes use a topcoat, basecoat and a process that changes the surface tension of the part to be metallized
- •Adhesion is identical for all process
- •Definition achievable is the same for all processes
Which process is best for my project?
Aesthetically, all processes yield nearly identical results, so this is not an easy answer.I have seen some excellent work done with all process and wont bash any as they are all tested and true processes.
With over 70 years of metallizing under our belts, Miller is one of the oldest metallizers in the US and we have knowledge passed down from one generation to the next.
All the processes are very similar and getting best quality results are all about controlling the process, no matter the process being used.
Miller is now a Silver Reduction metallizer, and in the past we had a vacuum line.Each process has its advantages and disadvantages from an operating standpoint.There are only a few, specific types of work that favor different processes.
The processes are mostly interchangeable and there are no discernible differences when it comes to quality, adhesion and the overall results will be the same with any of these processes.