链接：我该多久换一次琴弦？【世界级吉他制作大师专访】 – 王子晨的文章 – 知乎专栏【世界级吉他制作大师Abraham Wechter的访谈节目第四集，这周Wechter先生一直在忙，没能抽出时间面谈。

这集的内容是以邮件的形式给我发过来的，所以没有录音了。

这次提到了吉他琴弦的选购、保养，还有一些小趣事】======================================================================最直接的回答就是，当琴声听起来没有你预想的那么好了的时候。

通常情况下，如果每个星期只弹几次的话，至少一个月一换。

如果每天都弹的话，每次换弦的间隔时间更短。

我认识几个职业音乐家，每完成一套组曲就换一次，一晚上会用掉好几副琴弦。

琴弦老化有以下几个原因：其中一个因素叫“金属疲劳”，因为金属弦在弹奏的过程中不断地经历“弯曲”和“伸展”，而使它的弹性逐渐降低。

某些合金比其他的金属更“抗疲劳”，能够使音质更长时间的保持“清亮”。

不同于其他软合金，磷铜就是这样一种“抗疲劳”的合金。

（琴弦的包装上一般都有“92/8”这样的标示，其含义是这种琴弦由92％铜/ 8％的锡组成。

磷铜是在青铜基础上做了磷化处理，工艺比较复杂）另外一个因素是，裹在琴弦（内芯弦）外层的线圈变得越来越松弛。

弦芯的横截面大部分呈六边形，而不是圆形，目的是为了让外层的线圈更能紧紧地“咬合”住弦芯（增加了外层线圈与弦芯的摩擦力）。

但无论如何，最终外层线圈还是会松开，这时候琴声就开始变得浑浊无力。

手上的泥垢还有汗水，存积在外层线圈里，也会让琴弦变得反应迟缓，缺乏弹性。

最后一条，人体产生的酸还会和金属产生化学反应。

我们当中的有些人的身体的化学性质比普通人更具酸性。

记得我当时在吉普森（Gibson）的技术研发部工作，我的一个同事弹奏短短的几分钟，就能让琴弦变黑。

所以大家经常邀请他来为新研发的琴弦做测试：如果琴弦在他的手中能活下来，那么基本上全世界人用起来就没什么问题了。

某些琴弦会涂上专属的高分子聚合物，用来延长琴弦的使用寿命。

这些被涂过的琴弦的售价要比未涂的琴弦高得多得多，当然考虑到它的使用寿命也大幅度的延长，其实还是值得的。

而这项技术自它首次引入到现在，也经历了一段漫长的道路。

在最初的时候，这种涂层会磨损的很厉害，甚至会剥离琴弦，尤其是在拨片常常光顾的地方，会起一层像汗毛一样毛绒绒的东西。

而且早期的涂料技术更倾向于“厚涂”，这让琴弦的声音听起来很沉闷，虽然寿命延长了不少，但是听起来就没有未镀膜的新琴弦那么好了。

不过这种镀膜技术已经大有改善，但即使到了现在，我不得不承认，考虑到音色纯正的问题，我更推荐未喷涂的80-20琴弦（青铜弦又称黄铜弦，这种材质的琴弦是比较传统的一种，一般琴弦的包装上会有“80/20”的标示，其含义是这种琴弦由铜80%/20%锌组成。

这种材质的琴弦音色明亮有穿透力，喜欢清脆音色的琴友可以选择这种材质的琴弦）。

然而它的寿命也更短，你得乐意去更频繁的去换琴弦。

不管是有涂层的，还是没涂层的，想要延长琴弦的使用寿命你必须要保持琴弦的干净卫生。

在你拿起吉他前，花点时间去洗个手先。

弹奏结束把吉他收起来前，用擦银布把琴弦上上下下擦拭干净。

不过，有时候，你需要的仅仅是一副新琴弦。

======================================================================The quick answer is when they don’t sound as good as you want anymore. Generally I’d say at least once a month if you play a few times a week, more often if you play almost every day. I know some professional musicians who change strings a few times a night, between each “set”.Strings go dead for a number of reasons.One factor is just “metal fatigue” or the decreasing elasticity of the metal as it is stretched and bent when you play. Some alloys are more resistant to this than others and can sound “bright” longer. I think phosphor bronze would probably be in this category, as opposed to softer alloys.Another factor is the loosening of the grip of the outer windings on the inner core wire. Core wires are most often hexagonal rather than round in cross section to allow the outer windings to “bite” in a little better but eventually the windings lose their grip the strings start sounding dull.Dirt or dried sweat gets built up in between the windings. This makes the strings less responsive and springy.Finally there is the chemical reaction between your body acids and the metal. Some of us have more corrosive body chemistry than others. When I worked in Research and Development at Gibson we had one co-worker who could make strings turn black in a matter of minutes. We often asked him to test new string sets- if they survived his touch we knew they were probably going to be OK for just about everybody.Some strings are coated with proprietary polymers to extend their effective life. These coated strings are often considerably more expensive than standard uncoated strings, but the trade off is they can last much longer. This technology has come a long way from when it was first introduced. Initially the coatings would sometimes fray and hang off the strings like strands of fine hair in the area where the pick would strike. Also the early coatings tended to be heavier and they dulled the sound of the strings, so they might last longer but never really sounded as good when new as uncoated strings. Coating technology has improved a lot but even now I must admit that for pure tone I still prefer an uncoated 80-20 bronze string. However they go dead much faster and you need to be willing to change strings much more often.One thing you can do to extend the life of your strings, coated or uncoated, is to keep them clean. Take a moment to wash your hands before picking up your guitar, and wipe it down with a polish cloth a little before you put it away.But sometimes you just need new strings ; – )