unevenness in paint or coating
Refers to blotchy, streaky, or inconsistent application of paint, varnish, nail polish, etc. Common in DIY, crafts, and cosmetics contexts.
When I painted the wall, I ended up with uneven patches.
マニキュアの塗りムラを直すのは難しい。
It's hard to fix unevenness in nail polish application.
Standard mixed kanji-katakana spelling; the katakana ムラ is common for the 'unevenness' meaning.
Hiragana variant; less common but still used.
Kanji 斑 is technically correct for 'unevenness' but rarely used in this compound; may be seen in older or formal texts.
Compound of 塗り (nuri, 'painting, coating', from 塗る nuru 'to paint') and ムラ (mura, 'unevenness'). The katakana spelling ムラ is conventional for the 'unevenness' sense.