Calculating mix ratios?

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PostPosted: Thu May 13, 2021 10:14 am
NightTrain wrote:
NFT5 wrote:.......which required 300g primer, 48g activator and 45g thinner. That's a 4:1:1 mix. Weighing it out is much more accurate.........

Not to be labeled a critical math instructor, but wouldn't that actually be
a 6:1:1 mix? I'd call it a typo... :lol:

This discussion brought back memories of watching my Dad mix paint.
He used the calibrated eyeball method, whereby he would dip the paint
stir stick into the mix, pull it up and watch how the paint dripped and
flowed off the stick. If it appeared too thick, he would add reducer. If too
thin, add more paint. He painted professionally for several years and was
very good. This was back in the old days when you would punch a hole
in your mask for your cigarette.


i see what NightTrain is talking about 48g is 1/6th of 300g thus the 300g is 6, the 48 is 1, and 45g is 1. you get 6parts 300g: 1 part 48g: 1part 45g 6:1:1
Jay D.
they say my name is Jay

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PostPosted: Thu May 13, 2021 9:30 pm
Yep Jay, that's how I read it.

Chris probably meant the 300g primer to be ready-to-spray.
That would calculate correctly.
"If you can't move it, paint it." - U.S. Army

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PostPosted: Thu May 13, 2021 11:50 pm
It would be 6:1:1 on weight but the formulation of 4:1:1 is for volume. Since the primer (out of the tin, not activated or reduced) is so much heavier then it takes about 1.5 times the weight to get the equivalent volume.

So, 1 litre of primer weighs about 1.5kg while the reducer and thinner, per litre, actually weigh less than 1kg since they're actually lighter than water.

Don't ask me to do those numbers in Imperial measurements - we gave those up 50 years ago.
Chris

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PostPosted: Fri May 14, 2021 9:39 pm
Got it, Chris. Volume vs weight. Thanks for elaborating.
I was thinking of the jobber mixing paints by weight,
and the applicator mixing (paint/reducer/activator) by volume.

Now is it a bonnet or hood? Or boot or trunk?
And how in heck can a car have wings? :lol:
"If you can't move it, paint it." - U.S. Army
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