There are numerous approaches to shinai preservation and maintenance. Some people recommend immersing the bamboo in oil, some talk about taking the shinai apart and coating the inside surfaces, others believe that the edges of each take should be sanded down before use.
Kenshi who use oil seem to have their own favourites. These include purpose made shinai oil, light engineering oil, linseed oil, cooking oil and various other alternatives. Over the years I have tried most of these and I am yet to be convinced that any of these lubricants or any the above application methods make the slightest difference to the health or longevity of the shinai.
It may well be that the oilers have got in right and that I am part of an ignorant minority, but the only pre-use precaution that I try to take with shinai is to keep them for 6 months or so for the take to adjust to the difference in humidity. This is not always possible when I need to buy last minute replacements.
Obviously shinai need to be regularly inspected and broken take need to be replaced. Those that are just slightly splintered at the edge can be rubbed down with sandpaper or with a purpose made shinai file. It also helps seal the edges if you run a hard metal object along the repair. This compresses the bamboo fibres to stop further splintering. These repairs are often completed with the application of more oil or wax, (there is a school of thought that believes that applying candle wax to the repair will keep everything in place).
Going to these lengths shows a commendable concern for your own shinai, but does not necessarily show the same level of regard for your opponents’ bogu. I have turned up to a number of special occasion keiko in my Sunday best handmade bogu only to find wax stripes on my men or kote afterwards. These do give a clear record of where I was hit and may even replace shiai referees in the future; on the other hand they are almost impossible to remove without damaging the armour.
So please when you oil or fix your shinai, make sure it is wiped dry. And keep away from candle wax, unless the lights go out.
While we are talking about shinai repairs I have a question that has puzzled me for years. Why when shinai bend do the ends point downwards in the opposite direction to the tension of the tsuru? Does anyone know the answer?