THE LEARNING CENTER
Oiling Points
Contributed by member Aaron Kilander / MPK Enterprises
When one refers to oiling point’s, that is referring to soaking them in mineral oil. Especially in the case of points from the Deep South, it is common to run into cases where a piece may have been soaked in mineral oil. At times points from other areas may be soaked as well, like on some Mayan artifacts, specifically the eccentrics that many times pick up a heavy white patination.
Reasons for Oiling Points
The main reason for soaking points in mineral oil is to bring out the materials original color, and many times translucency that may go unseen otherwise. It can drastically change the way a point looks and bring out many colors that may have been hidden beneath a white or off-white colored surface. This can in some cases bring the value of pieces up depending on what is revealed once oiling is complete. Not all results are desirable ones as well.
What Oiling Does to an Artifact
Many times points pick up a heavy white or off-white patination that tends to cover a piece and hides the original materials color and translucency. Soaking them in mineral oil basically causes the patination to become translucent and reveals what the true underlying color is. In many cases a piece will become translucent or reveal bright and vibrant colors once the patination clears up during the soaking process. Oiling points can take very different lengths of time as well. In the majority of cases a piece can be fully changed in less than 24 hours. It is not uncommon though for a piece to take several days or a week as well. It depends greatly on the porosity of the piece and how willing it is to absorb the mineral oil. We have personally had to soak pieces for extended durations that took a month or longer in order to obtain the desired results, but is not the norm. Mayan artifacts I have found tend to take several days instead of a quicker turn around time, and not all pieces will turn as well. Some artifacts will also not give a desirable result either if the material under the patina is gray, or just plain white itself. Many times a completely white artifact can become a completely different color.
The Long Term Effects of Oiling
The changes that take place when oiling a piece is not permanent and will turn back to its original state in time. Some pieces turn back quicker while others may take much longer. I have had some start to change back within weeks while others would take months to see a change going back. Once that change back has started, it is not a quick change either. Some pieces may take years to revert back to its unaltered state. Basically, as the oil dries out of the piece, the patination will slowly begin to turn back to its original color instead of being clear.
Removing Oil from an Artifact
There are many different practices of helping to remove oil from a piece for different reasons. One common practice is to dip it in acetone which can greatly accelerate the drying out process and help to remove some of the mineral oil from the piece. This is also a practice that I highly discourage as there can be drastic side effects to this method. Materials from some areas of the country are fairly durable and acetone is a common used substance which leaves the material unharmed basically. Many materials from the Deep South are more porous and the acetone can penetrate into the piece too much and actually break some materials down, especially some of the chalkier cherts. We have personally seen prominent serrations literally fall off a piece from Florida after being cleaned with finger nail polish remover, which also has a significant acetone content in it. It was a chalkier chert that had a fair amount of polish on it and someone did not recognize the potential for it to be greatly damaged. Deep South relics also tend to have less deposit and age on them due to the vary different environment they have been exposed to, and can be easy to over clean a piece as well. The method I recommend is a warm bath with mild soap. Put some warm water in a bowl with mild soap and just rub the piece lightly with your hands. That in itself will not remove all the oil from a piece and oil that is deeper in the material will surface later. It will however accelerate the drying out process by removing the oil from the surface area. Other than that method, time is just the only other safe way.
Some Misconceptions about Oiling
Some think that oiling a piece can ruin it or is a permanent thing. Neither is correct. Results may not always be desirable ones, but will correct in time. Some also feel that oiling makes one unable to determine authenticity. Oiling a point can make it harder to judge a relics authenticity at times when oil is present at the surface of the piece, and does have a tendency to make re-chipping more hidden from view. Many times just drying the piece with a towel will remove enough oil from the surface to allow an accurate evaluation. More oil will come back to the surface in time after drying it off. If drying it off is not sufficient, then a warm soapy bath as described earlier will give the desired effect and allow an accurate evaluation. Oiling does not remove the patination but only causes it to turn clear temporarily.
Before and After Pics
(these pieces were already soaked previously and were much whiter to begin
with)
(clink images to enlarge)
