Why You Should Not Use 100-Grit Files on the Natural Nail
Walk into enough training rooms and you will still find someone reaching for a 100-grit file to prep a natural nail. It is one of those techniques that survives purely because it is still being taught — not because it makes any sense with modern products. If your trainer hands you a 100-grit file for the natural nail plate, that tells you something important about how current their training is.
What "grit" actually means
The grit number is simply how coarse the abrasive is: the lower the number, the rougher the file and the deeper the scratches it leaves. A 100-grit file is aggressive. It is designed for shaping hard material and reducing product quickly — not for touching the delicate surface of a living nail. Look at the scratches a 120-grit file leaves on the nail plate under magnification and you can already see the damage; drop to 100 and it is worse again.
The natural nail plate is not a surface you need to rough up to work on. Every deep scratch you put into it is thinning it, weakening it, and giving irritants an easier route in. You are not "keying" the nail — you are wounding it.
Why anyone ever did this
There was a time when heavy filing made sense. Twenty or thirty years ago, gels and acrylics had poor adhesion, so technicians compensated by roughing up the plate aggressively and using harsh acid-based primers to get product to stick. Both were workarounds for weak chemistry.
Modern products have moved on completely. Today's systems have far better adhesion — some need no primer at all — and they achieve it without demanding that you tear up the natural nail first. The technique became obsolete years ago. The teaching, unfortunately, did not always keep up.
The primer point, while we're here
The same logic applies to acid primers. A professional simply should not be reaching for an acid-based primer on a natural nail as a matter of routine. The real culprit behind so much of the "gel damaged my nails" complaint is not the gel at all — it is the combination of over-filing and methacrylic acid primers attacking the keratin and the amino acids the nail is built from. Blame the prep, not the product.
If a natural nail needs a 100-grit file and an acid primer to hold product, the answer is almost never "file harder" — it is better products and better technique. Over-preparation is one of the most common causes of thin, sore, damaged nails, and it is entirely avoidable.
What good prep looks like now
- Remove shine and surface oil with a fine buffer — think 180 or higher on the natural plate, not 100.
- Dehydrate and use a modern, well-formulated bonder rather than a harsh acid primer.
- Let the product chemistry do the adhesion work it is designed to do, instead of relying on abrasion.
Prepped this way, the natural nail stays thick, strong and healthy underneath your work — and your retention is usually better, not worse, because a damaged plate is not a reliable foundation to begin with.
Choose your trainer carefully
This is exactly why it matters who you learn from. Techniques like the 100-grit file and the routine acid primer are hallmarks of training that is stuck in the 1990s. Before you book a course, ask what prep the trainer teaches on the natural nail and why. If the honest answer to "why" is "because that's how we've always done it," keep looking. Doug Schoon's Face to Face with Doug Schoon, now available in several languages, is a good, science-based reference for understanding what filing actually does to the nail plate.
Talk to us
If you want to move to a gentler, modern prep routine — or you're not sure which of your current products still rely on old-fashioned abrasion — we're glad to help.
- Email: help@ikoniqnails.com
- WhatsApp: +49 160 649 7218
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