There are many things in life that reward a bit of DIY spirit. A loose hinge, perhaps. A wobbly chair. Even a set of shelves, if one is feeling particularly bold on a Sunday afternoon.

But there are also things that fall into a rather different category. You might change a lightbulb - perfectly sensible. You might even rewire a plug. But you wouldn’t, one hopes, decide to rewire the entire house after watching a ten-minute video and feeling quietly confident.

And yet, in the world of old paintings, something rather similar happens with surprising frequency. 

We see them often. Paintings that have, at some point in their lives, encountered an enthusiastic pair of hands. The results are rarely subtle. A face may gleam with an unexpected vigour, as though freshly returned from holiday. Shadows become curiously assertive. Details, once softly suggested, are now declared with all the delicacy of a permanent marker.

It is, one senses, done with the very best of intentions. After all, the impulse is understandable. A painting appears dark - so one cleans it. A small loss of paint - so one fills it in. A varnish looks uneven - so one applies another, just to tidy things up. Simple enough, one might think.

But here's the truth: paintings are not surfaces in the everyday sense. They are structures - delicate, layered, and often centuries old. Beneath what you see lies a complex arrangement of ground layers, pigments, binders, glazes, and varnishes, each with its own chemistry and behaviour.

To intervene in that structure without training is the equivalent of repairing a watch using cutlery. One might succeed in moving things around, but not necessarily in improving them.

Cleaning, for instance, is not simply the removal of dirt. What appears to be grime may in fact be an original glaze - a deliberate tonal adjustment applied by the artist. Remove it, and one does not reveal the painting, but alters it. Permanently.

Retouching is equally treacherous. Matching colour is only the beginning. One must consider ageing, reversibility, and the behaviour of materials over time. What looks convincing today may, in a few years, bloom into something quite different - like a well-meaning but ill-judged haircut. As some of us may remember from the 1980s.

And varnishing - perhaps the most deceptively simple of all - can seal in problems, distort colours, or create a surface that future conservators must painstakingly undo.

Professional conservators, such as Holly here at Brave Fine Art, approach these works with a very different mindset. The goal is not to make a painting look “new”, but to preserve what remains, stabilise what is vulnerable, and ensure that any intervention can be reversed in the future. Often, the best decision is to do less.

So when we encounter a painting that has been… enthusiastically improved, we don’t sigh in frustration so much as reflect on the optimism behind it. Someone, at some point, cared enough to try.

But paintings, like houses and bodies, have their limits. There comes a point where goodwill must give way to expertise. By all means, put up the shelf. Change the lightbulb. Even have a go at that slightly ambitious flat-pack.

But when it comes to a 200-year-old painting, quietly holding together layers of history beneath its surface…

…it may be best to step away from the varnish.