Why a blog post, talk, preprint or pitch can cost you a patent: the US one-year grace period, Europe's absolute novelty rule, and what to file first.
File first, then talk. A provisional application costs little and fixes a filing date; anything you make public before that date can be used against you, and outside the US it usually cannot be undone.
Your own public disclosure made one year or less before your effective filing date is not prior art against you (35 U.S.C. 102(b)(1)(A)). Relying on it is still risky: you must be able to prove the disclosure was yours, a third party may build on what you published and file first, and the grace period does not carry over to most other countries.
Under the European Patent Convention, anything made available to the public before the filing date is prior art (Art. 54 EPC), including your own talk, preprint, demo or post. The exceptions are narrow: an evident abuse against you, or display at an officially recognised international exhibition, each within six months (Art. 55 EPC). A few countries offer limited grace periods with conditions; check before relying on one.
A pitch to a small group under a written confidentiality agreement is generally not a public disclosure. A pitch deck sent around freely, or posted, may be.
A provisional that describes the invention fully, with drawings, before any disclosure. It secures priority only for what it describes (35 U.S.C. 112(a)), so a thin one written in a hurry protects little. Within twelve months, file the nonprovisional or an international (PCT) application that claims its benefit.
Draft a disclosure, freeSee a real run