Brush Stops Painting White

[hello]

Hi there. I have just started using the trial of Affinity Photo and so far I quite like it. Coming from 17 years of PS I find it very intuitive. But I'm having an issue with the paint brush tool. After a while it refuses to paint in white. Yes, only pure white. It will paint other colours just fine, including black and the lightest possible grey. If I paint with white nothing shows up. As soon as I switch to any other colour or shade of grey it paints no problem. 

 

This happens on masks and pixel/background layers. 

 

I have the flow and opacity both at 100%. Protect Alpha is unchecked. Blend mode is normal. But it can't be those settings, because as I said, every other colour except white will paint fine. If it were a problem inherent in my settings I assume it would effect all other colours, too.

 

If I quit and restart it goes back to normal and will paint with white, but after a while it stops again. If I open a 

 

Any ideas? I've never come across this issue in any editing software before. Did I break it?  

 

Edit: Nevermind. Apparently there's some RTFM-ing I need to do. Looks like I hit the crossed out circle next to the main swatches on the colour palette and it took away my white painting ability. Mods can feel free to delete this post if you like. 

 

[R C-R]

7 hours ago, hello said:

Looks like I hit the crossed out circle next to the main swatches on the colour palette and it took away my white painting ability.

To spare you reading the 'fine' manual for this, the red slash through a white swatch icon is a button that sets the current color to transparent (effectively no color).

[hello]

2 hours ago, R C-R said:

To spare you reading the 'fine' manual for this, the red slash through a white swatch icon is a button that sets the current color to transparent (effectively no color).

 

Ah-ha! I thought it might be something like that. Not sure why I'd want to paint without painting, though. Perhaps it's for people training to be mimes.  

[lepr]

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[R C-R]

1 hour ago, owenr said:

It is useful for setting the fill or stroke of vector objects to none.

Technically, perhaps it makes more sense to say it sets the color of the stroke or fill of objects to none (or to 0% opacity or to 100% transparency)? Consider this Phantom shapes.afphoto file or a screenshot of its selected layers:

 

The curve, rectangle, & star shapes each have a 20 px wide stroke; the text has a 120 px height. All are invisible because their stroke & fill colors are set to 'none' but that can't mean those object properties no longer exist ... can it? 

[lepr]

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