Do the formulas still work in the copy?
Formulas outside the masked cells are kept. A masked cell becomes text, so a formula that calculates with it may show an error: mask the result rather than the inputs when the calculation must stay.
Guide
How to redact an Excel spreadsheet
Hiding a column or deleting a few cells rarely removes data from a workbook. Here is where an Excel file keeps it, and how to produce a copy without it.
Updated
In short
- A hidden column or sheet is still in the file.
- Pivot tables and charts can keep their own copy of the data.
- A column header such as Name or IBAN tells the detection what the column holds.
- Check the copy: unhide everything, search it, read its properties.
Hiding is not removing
Hiding a row, a column or a sheet, giving cells a white font, or narrowing a column changes what is displayed, not what is stored. Anyone who receives the file can unhide them in a few clicks.
Where a workbook keeps information
- hidden sheets, rows and columns;
- comments and notes, with the names of their authors;
- headers and footers, which only show when printing;
- sheet names, which often carry a client's or a person's name;
- pivot tables and charts, whose caches keep a copy of the source data even after the source is deleted;
- formulas and links to other workbooks, which can name a file or a folder;
- the document properties: author, company, last modified by.
Redacting an Excel file with Obscelis
Import the .xlsx file. Each sheet becomes a page, hidden sheets included, with its rows, then its header and footer, comments and drawings. The header of a column is used as context: a column titled Name, E-mail or IBAN helps the detection of the values under it, and a decision can be applied to every occurrence of the same value at once.
The copy is a workbook again. A masked cell is written as text with its masked characters replaced by █; if it held a formula, the formula is dropped. Pictures have their masked areas painted black, embedded objects are emptied, and the properties and the names of comment authors are cleared unless you choose to keep them.
Obscelis then opens the copy again and searches every part. Pivot table and chart caches are not reviewed: if one still holds a masked value, the verification finds it and refuses the copy. Delete the pivot table or the chart, or refresh it from data without the values, then export again.
Check the copy before sending it
- Unhide every sheet, row and column.
- Search the whole workbook for each masked value.
- Look at the pivot tables and charts that remain, and at the comments.
- Read the properties in File › Info.
Questions
Is a CSV export of the sheet safer?
A CSV keeps only the values of one sheet, which removes comments, hidden sheets and caches. Obscelis reads CSV files too, and masks their values the same way.
Can Obscelis open .xls files?
Not yet. Save the workbook as .xlsx in Excel, then import it.
Other guides
Masking an IBAN, a NIR or a SIRET in a document
Bank details, social security numbers and company numbers sit in payslips, statements and invoices. Each says more than it seems, and each has a check digit that helps find it.
How to redact a Word document permanently
A black highlight in Word hides a word on screen and leaves it in the file. Here is where a Word document keeps information, how to remove it, and how to check the copy.
Why a black box over text does not redact anything
Drawing a black rectangle over a name hides it on screen, and nowhere else. The text stays in the file, one copy and paste away.
Try Obscelis for 30 days
Download it for macOS, Windows or Linux: the trial needs no account and no card. A question, or a demonstration for your team? Write to us.
Download ObscelisWrite to us
latelierdudev.contact@gmail.com
Opens your e-mail app. We only use your address to reply.