Painting Fin for White Balance

I want to paint one of my fin blades white to use for white balancing while  I dive while keeping both hands on the camera.   Is there a particular "shade" of white that would  be the most color accurate for this?   And what brand of paint  would be good for plastic?

Thanks!

If you want proper paint to cover all of your fins, use boat paint (polyurethane?) but it's so expensive that you might as well buy a new set of white fins.

Otherwise, use a paint pen marker (<10$) which works on most surface and color a small zone of the fin, that should do the trick

I just got a set of white fins to use for that.  As a plus, it is easy for my wife to recognize me with a quick glance.

I put a piece of white tape from Home depot on a fin. That was OK, I prefer to use a grey card (X-rite color checker w/Neutral Grey) at depth and multiple times when profile changes. Have a thin bungee cord thru the card and can slip on wrist or secure to BC when I'm done white balancing and shooting the color pallet. I really haven't used the color pallet in post yet. I hear I could build a color profile based on the x-rite in Resolve. Maybe one day.

I used to used to stitch a piece of white cloth on my fin and I found it tricky but workable.

Now I use a gray glove and do WB between the subject &  my GH5s. It is one haded operation. This way the WB is more accurate since it is taking in the same lighting  as of the subject ( I shoot in ambient lighting).

I don't know about a specific shade of white and/or whether the brand of camera would matter to the question.  But, WB on my video housing is not doable with one hand so I've never been able to use a slate and have always relied on finding some sand or other "white 'ish" object.  When I saw a couple on our 2019 trip with white fins, I was like, that's the answer!  Bought a pair a year ago and finally had a chance to use them just a few weeks ago.  For my rig, it has worked like a charm!  It didn't hurt that the fins worked so well (out swam my husband without meaning too on the first dive with them, getting them on/off is so easy, etc.), my husband bought a pair the week we got back to town!

Technically you want a neutral white - in fact it doesn't have to be white - just neutral  which basically means the RGB values are all equal or close to it.  You could achieve this in paint by taking a white card (many grey cards will have a white back)  to a paint shop and asking them to match it, most big shops will have a scanner to scan paint chips and match colours. 

I think the problem with painting a fin is that fin flexes so the paint needs to accommodate that.  Probably a lot simpler to use a white fin.

A significant question is the shooting distance. If you use white fins on your own feet, will that white balancing match your actual shooting distance?

I have noticed this problem because my white balance card is relatively small and I need to "white balance" it from a very short distance with my WACP wide angle lense. In ambient lighting the difference from actual shooting seems relatively small.

But when using videolights, the perfect white balance at short distance does not match that of actual shooting distance. When shooting with videolights, the light has to travel from the lights to subject matter and back to the camera. If the subject matter is at say 2 meters distance, e.g. a ship wreck or other scenery,. the total light travel distance is 4 meters, which is significantly different from shooting a grey card at 0.2 meter distance. Thus the colors of subject matter will not be as vibrant.

I like the idea of white or grey fins, but with a wide angle lense they will fill less than 5% of screen area. But, considering that a 130 degree wide angle lense will easily cover an area equivalent to a queensize bed, should I bring with me a queensized white sheet with me?? Ha ha.

Obviously this gets more complicated when there is a combination of video light and ambient light.

For single picture still photography this might be less of a problem because you might want to let the background to fade to blue or whatever is the dominant background color. But for shooting 3D underwater photogrammetry this is a problem because you would want to use true colors of the subject matter irrespective of the distance. 

Incidentally the Aquatica/Amphibico metallic white balance card has a prefabricated green/bluish color cast. This does slightly help in matching the final shooting distance for proper white balance. I have just recently learned to appreciate this.