Support
Last updated: 13 May 2026
Need a hand with Undertint, or spotted something that doesn’t behave the way you’d expect? Get in touch and we’ll do our best to help.
How to get in touch
The fastest way is by email:
If you’re reporting a bug, please include the iPhone or iPad model you’re using, the version of iOS or iPadOS, and a short description of what you were doing when the issue happened. A screenshot is always helpful.
Common questions
Does Undertint need an internet connection?
Day to day, no. Undertint runs entirely on your device and photos never leave your phone or iPad. The only network activity is when you buy or restore Undertint Pro, which is handled by Apple’s StoreKit.
Which paints does Undertint know about?
The first release includes paint catalogues for Winsor & Newton Professional Watercolour, Holbein Artists’ Water Color, and Daniel Smith Extra Fine Watercolors. More brands and ranges will be added over time.
How accurate are the recipes?
Recipes are calculated using Kubelka-Munk pigment mixing from spectral measurements of each paint, which gets you closer to a real-world mix than any RGB-based estimate. They are still a starting point, not a replacement for testing on the page. Differences in paper, water ratio, and brushwork all affect the final colour.
Does Undertint collect any data?
No. There are no accounts, no analytics, no advertising, and no third-party tracking. See the privacy policy for the full details.
In-app purchases
How do I unlock Pro?
Open any colour in Colour Detail. The marketing card next to the single-paint recipe has an “Unlock Pro” button that opens the purchase sheet.
I bought Pro on another device and don’t see it on this one.
Tap “Restore Purchases” on the paywall, or open the About screen (info icon on the Palette view) and tap “Restore Purchases” there. Apple’s StoreKit reconciles your account and the unlock applies immediately. Make sure both devices are signed in to the same Apple ID.
How do I get a refund?
Refunds for in-app purchases are handled by Apple. Go to reportaproblem.apple.com, sign in with your Apple ID, find the Undertint Pro purchase, and follow the refund flow. Stach Ltd cannot process refunds directly.
Response times
Undertint is built and supported by one person. Most emails get a reply within a few working days; complex issues may take a little longer.
Contact
Justin Stach
Email: hello@stach.ltd