I know that this forum is focused on WWII but I thought that, despite this being a WWI helmet, the process of restoration would interest a few WWII helmet collectors.
I was asked to look into the prospect of removing the post-war varnish coating on this German M16 camo helmet because of my experience as a paintings conservator. Partly the reason I agreed to examine it was because I found it worrisome that a lot of collectors are using commercial stripping products and other harsh solvents to do similar work. These chemicals are not a good idea because they dissolve paint indiscriminately and too easily damage (skin) the original surface. I have seen many situations where a good portion of what the person was trying to save had been removed along with the old overpaint or varnish. If I could stress one thing, it would be that no single chemical or product will work safely in every situation. There are lots of variables that need to be figured out first.
On this particular helmet, a thick varnish had been applied many years ago and had darkened over time. Testing indicated that the varnish contained a drying oil. Drying oils, such as linseed oil, crosslink as they age and can become very difficult to remove from painted surfaces. The reason is that the solubility parameter of the aged oil varnish is usually overshadowed by the solubility parameter of the binder in the underlying paint. This was true for the M16 helmet. In other words, any solution successful in dissolving the varnish, when applied directly to the helmet, would also dissolve the underlying original paint.
Coming up with a treatment plan for this helmet required me to think about things in a different way. I tested the idea of using an organic solvent as a gas rather than as a liquid. After numerous tests, the idea worked and was successful in removing the varnish safely. With the proper timing, I could separate the varnish layer while preserving the original paint along with its preexisting scrapes, chips, and stains.
One thing I’d like to mention is that because this is a customized treatment, it shouldn’t be considered a template on how to restore other helmets. Unfortunately, there is no one-size-fits-all approach to cleaning and restoration. Using this method on another helmet could be completely ineffective or, worse yet, it could cause serious damage.
I will post some photos, and edit in some additional comments later. I hope you find it interesting. Thanks to the owner of the helmet for his interest in sharing this project with other collectors.
Mike
I was asked to look into the prospect of removing the post-war varnish coating on this German M16 camo helmet because of my experience as a paintings conservator. Partly the reason I agreed to examine it was because I found it worrisome that a lot of collectors are using commercial stripping products and other harsh solvents to do similar work. These chemicals are not a good idea because they dissolve paint indiscriminately and too easily damage (skin) the original surface. I have seen many situations where a good portion of what the person was trying to save had been removed along with the old overpaint or varnish. If I could stress one thing, it would be that no single chemical or product will work safely in every situation. There are lots of variables that need to be figured out first.
On this particular helmet, a thick varnish had been applied many years ago and had darkened over time. Testing indicated that the varnish contained a drying oil. Drying oils, such as linseed oil, crosslink as they age and can become very difficult to remove from painted surfaces. The reason is that the solubility parameter of the aged oil varnish is usually overshadowed by the solubility parameter of the binder in the underlying paint. This was true for the M16 helmet. In other words, any solution successful in dissolving the varnish, when applied directly to the helmet, would also dissolve the underlying original paint.
Coming up with a treatment plan for this helmet required me to think about things in a different way. I tested the idea of using an organic solvent as a gas rather than as a liquid. After numerous tests, the idea worked and was successful in removing the varnish safely. With the proper timing, I could separate the varnish layer while preserving the original paint along with its preexisting scrapes, chips, and stains.
One thing I’d like to mention is that because this is a customized treatment, it shouldn’t be considered a template on how to restore other helmets. Unfortunately, there is no one-size-fits-all approach to cleaning and restoration. Using this method on another helmet could be completely ineffective or, worse yet, it could cause serious damage.
I will post some photos, and edit in some additional comments later. I hope you find it interesting. Thanks to the owner of the helmet for his interest in sharing this project with other collectors.
Mike
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