Articles
The Flint PDF library
Short, practical pieces on PDFs — fixing a typo, signing a contract, getting a file under 25 MB, picking the right format, dealing with awkward scans. 965 articles and counting.
What is PDF OCR?
How software reads a scan and turns the pictures of words into actual words.
3 minReadWhat is PDF/X?
The print-shop variant of PDF, explained for anyone who's been asked to supply one.
3 minReadWhat the little icons on a PDF mean
A quick decoder for the symbols PDF viewers love to sprinkle around.
3 minReadWhen free PDF tools stop being free
Every 'free' PDF tool has a wall. Here is what those walls look like — and the cheapest way past.
4 minReadWhen to pick a day pass vs Pro plan
A simple rule of thumb plus break-even maths for choosing between a Flint day pass and Pro plan.
4 minReadWhen to use a PDF vs a Word doc
A quick guide to picking the right format for the right purpose.
3 minReadWhen to use a PDF vs an EPUB
Two ebook formats, two different jobs. Picking the right one matters more than you'd think.
3 minReadWhen to use a PDF vs an image
PDF for documents, image for visuals — but the lines blur. Here's the rule of thumb.
3 minReadWhen to use a PDF vs Google Docs
Quick rules for picking PDF or Docs depending on where the document is in its life.
3 minReadWhen was the PDF invented?
A potted history of the PDF, from a 1991 office memo to the format running your inbox today.
3 minReadWhen you need a qualified electronic signature
Most contracts don't need a Qualified Electronic Signature. Here's the short list of cases that do.
4 minReadWhere do online PDF editors store your files?
The honest answer for most online PDF tools: somewhere on someone's server. Here's how to find out where.
4 minReadWho should actually pay for a PDF editor?
Not everyone needs a paid PDF editor. Here is who actually benefits and who can stick with free tools.
4 minReadWhy are some PDFs locked?
Not all locked PDFs are the same — here's how to spot what kind you've got.
3 minReadWhy black rectangle redaction isn't enough
Black rectangle redaction has caused some of the most famous PDF leaks. Here's how it goes wrong.
4 minReadWhy can't I copy text from this PDF?
Three reasons text won't copy from a PDF, plus how to fix each one.
3 minReadWhy can't I edit this PDF?
Stuck staring at a PDF that won't let you change a thing? Here's why.
3 minReadWhy does my converted PDF have no text layer? Add searchable text
Image-only output happens when conversion rasterises text. OCR restores searchability.
3 minReadWhy does a converted PDF have wrong fonts? Restore the typography
Wrong fonts post-conversion mean fonts weren't embedded. Re-export with proper embedding.
3 minReadWhy do PDFs look different on different devices?
The 'P' in PDF stands for portable — so why do they keep shifting on you?
3 minReadWhy do PDFs sometimes have weird fonts?
Mystery fonts in your PDF? Here's the simple reason behind them.
3 minReadWhy do some PDFs ask for a password?
The story behind password-locked PDFs and what to do when you hit one.
3 minReadWhy do some PDFs have blue text with underlines?
Blue + underline = a clickable link. Here's how PDFs handle hyperlinks.
3 minReadWhy emailing PDFs isn't really secure
Email is the most common channel and the least secure. Here's why — and what to do about it.
4 minReadWhy does Excel to PDF cut off columns? Fit it all on the page
Wide Excel sheets need page-fit settings or landscape orientation. Set before export.
3 minReadWhy is my PDF blank? Diagnose and recover the missing content
A blank PDF is almost never truly empty. Diagnose the cause and recover what's hiding behind the white pages.
4 minReadWhy is my PDF blurry? Restore sharp text and images
Blurry PDFs are almost always a resolution or compression problem. Spot which and get sharp text back.
3 minReadWhy is my PDF converting with extra pages? Stop the page bloat
Extra pages on conversion come from page-break mismatches. Adjust source or post-process the output.
3 minReadWhy is my PDF displaying the wrong orientation? Fix it permanently
Wrong-orientation PDFs have rotation metadata that doesn't match the content. Rewrite once and it displays correctly forever.
3 minReadWhy is my PDF form not saving? Keep filled fields filled
Forms that don't save use restricted templates or are filled in viewers that can't write. Flatten and resave properly.
4 minReadWhy is my PDF larger than the original? Stop the size inflation
PDFs grow during export when source apps embed extras. Re-export smart or compress after and the bloat disappears.
3 minReadWhy is my PDF loading slowly? Make every page open instantly
Slow PDFs are bloated PDFs. Compress them once and they open instantly forever.
3 minReadWhy is my PDF not attaching to email? Fix the upload now
PDFs that won't attach usually exceed size limits or trip security filters. Shrink or share differently.
3 minReadWhy is my PDF not displaying fonts correctly? Fix font substitution
Wrong fonts mean the PDF didn't embed them. Rebuild the file with proper embedding and your design returns.
3 minReadWhy is my PDF not loading? Diagnose the stall and fix it
PDFs that won't load are usually too big, partially downloaded, or hitting a viewer bug. Identify the cause and unstick it.
3 minReadWhy is my PDF not opening? Causes, fixes, and recovery steps
When a PDF refuses to open, the file itself is usually fine. Here's how to figure out what's blocking access and get it working.
4 minReadWhy is my PDF not printing in colour? Restore full-colour output
A PDF that prints monochrome usually has a print setting forcing greyscale. Fix it at print or rebuild the file.
3 minReadWhy is my PDF not searchable? Add a text layer in seconds
Unsearchable PDFs are image-only. Add a text layer with OCR and the find function works again.
3 minReadWhy is my PDF printing blank? Fix the print without the white pages
A PDF that prints blank has content the printer can't render. Re-flatten the file and it prints cleanly.
4 minReadWhy is my PDF rotated? Fix sideways pages permanently
Sideways PDFs aren't your viewer's fault — the rotation lives in the file. Rotate it permanently in one step.
3 minReadWhy is my PDF saying it's corrupt? Recover the content
Most 'corrupt PDF' errors come from truncated downloads or partial writes. Repair or rebuild and the content comes back.
4 minReadWhy is my PDF so large? The real reasons and how to shrink it
Most oversized PDFs have one of three culprits. Spot which one yours is and shrink the file in a single step.
3 minReadWhy is my PDF suddenly huge?
Why your tiny-looking PDF weighs the same as a movie, and how to fix it.
3 minReadWhy is my PDF text fuzzy? Restore crisp, sharp text
Fuzzy PDF text comes from raster fonts, soft scans, or rendering bugs. Sharpen it by rebuilding the text layer.
3 minReadWhy is my PDF text not selectable? Make it selectable in seconds
Unselectable text means the PDF is image-only. OCR adds a real text layer and selection works.
3 minReadWhy is my PDF too small to print? Get readable output at full size
A PDF that prints tiny has a page-size mismatch. Fix the scale setting or rebuild the file to print at full size.
3 minReadWhy is PDF everywhere?
Why this one file format quietly took over contracts, statements, forms and every government office.
3 minReadWhy Most People Misuse PDFs
Most PDF frustration comes from misusing the format. Here are the five common misuses and what to do instead.
4 minReadWhy does my encrypted PDF show blank? Diagnose the lock
Blank encrypted PDFs may have render issues separate from encryption. Unlock and rebuild.
3 minReadWhy doesn't my PDF signature show? Make it visible
Invisible signatures mean wrong placement, transparent ink, or wrong layer. Place visibly and flatten.
3 minReadWhy does PDF conversion take so long? Speed it up
Slow conversions usually mean large files or OCR work. Compress first or use a faster tool.
3 minReadWhy PDF passwords aren't perfect security
A password helps. It isn't a complete answer to every threat. Here are the honest gaps.
4 minReadWhy does PDF to HTML conversion look broken? Improve the output
HTML is structural; PDFs are positioned. Conversion always involves translation; better tools translate better.
3 minReadWhy PDF tools belong in the browser
PDFs arrive in the browser (email, Drive, Slack). The editor should be there too. Here's why browser-based wins.
4 minReadWhy people leave Adobe Acrobat (and where they go)
Most people do not cancel Acrobat because they hate it. They cancel because they barely used it. Here is the pattern, and where people land.
5 minReadWhy does PowerPoint to PDF lose animations? It always does
PDFs are static; PowerPoint animations are motion. Conversion can't carry motion. Use video for animated content.
3 minReadWhy does signature validation say modified? Understanding the warning
'Modified' means the file changed after signing. Sometimes intentional, sometimes alarming.
3 minReadWhy signing then editing invalidates the signature
A signed PDF is supposed to be frozen. Editing it breaks the seal by design.
3 minReadWhy does Word to PDF change formatting? Lock the layout
Word-to-PDF layout shifts come from font and export settings. Embed and standardise.
3 minReadWhy You Should Always Flatten a Shared PDF
An unflattened PDF is editable in ways that surprise people. Flattening on share locks the document as a final artefact.
3 minRead