mixing international perfection plus by weight

Ian_Edwards

Ian_Edwards

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I'm using International Perfection Plus clear varnish to coat some small components.

I only need about 30ml to 40ml per coat.

I find it much easier to measure out the components by weight on a small electronic scale than guess the volume.

The instruction say to mix by volume in the ratio 2 : 1.

I can't find any info' online about mixing by weight and there's nothing in the data sheets to tell me what the densities of the two components are, so I can't work out the ratio by weight.

I guess that the two components are of similar density, but it's expensive stuff and the extra work involved in recovering from a poor paint job would be significant.

Anyone out there who has a work around, or understands enough about polyurethane coating to know how critical the mixing ratios are?
 
Ian_Edwards said:
I'm using International Perfection Plus
The instruction say to mix by volume in the ratio 2 : 1.

I can't find any info' online about mixing by weight and there's nothing in the data sheets to tell me what the densities of the two components are, so I can't work out the ratio by weight.
Click to expand...

Gotta know where to look!

Part A has a relative density of 1.07

Part B has a relative density of 1.04
 
For even smaller quantities I used to use the translucent plastic containers that are used for films (remember them?). Just a little strip of masking tape on the outside with a mark at 1cm and another at 3cs from the bottom. Easy to see the level of the liquids inside the container.
For larger quantities there are plastic mixing cups that are already marked with various ratios and various quantities. The cups are cheap, come in various sizes and can be reused after the paint residual in the cup has cured; just flex the cup and the cured paint will pop free.
Why mess around with digital scales?
 
VicS said:
Gotta know where to look!

Part A has a relative density of 1.07

Part B has a relative density of 1.04
Click to expand...

Thanks Vic, that's around 3% difference in density, not much, but with my scales which have a resolution of 0.1gm, I should just about be able to take account of the difference. A typical mix would be 21.4gm of A and 10.4gm of B.

The problems solved, but as a matter of interest where did you find the info'? I tried a whole range of different search terms on google and could find the densities.
 
International Perfection Plus clear varnish
Part A (varnish) has a relative density of 1.07
Part B (hardener) has a relative density of 1.04
due to these informations concernig density given by Vic:
(hardener B_weight) = (varnish base A_weight) x 0,486

example (g for grammes units) :
For 100g varnish base A add 48,6g hardener B (48,6 = 100 x 0,486)
For 200g varnish base A add 97,2g hardener B (97,2 = 200 x 0,486)
with a kitchen scale (precision 1g),
1. reset scale to 0g
2. put the desired weight of part A (ex: 100g)
3. reset scale to 0g
4. add 48g ( calculated 100x0,486)
mix part A & B during 3mn, then wait 3 mn before applying the bi-component varnish to avoid bubbles
 
That's not correct, the mixing ration by volume is 2:1 for perfection plus, at least it was when I posted in 2017.
You have assumed 1:1.
If you mixed at 1:1, you'd soon run out of hardner and have a varnish that probably wouldn't set.
With a very small difference in densitity between Part A and part B, combined with the difficulty in measureuring small quanities of a viscose liquid (by weight or volume) accuratly, you can assume that a 2:1 by weight or volume will work.
I originally posted because I couldn't find the density in the manufactures data, Vic very kindly found that for me.
 
Ian_Edwards said:
That's not correct, the mixing ration by volume is 2:1 for perfection plus, at least it was when I posted in 2017.
You have assumed 1:1.
If you mixed at 1:1, you'd soon run out of hardner and have a varnish that probably wouldn't set.
With a very small difference in densitity between Part A and part B, combined with the difficulty in measureuring small quanities of a viscose liquid (by weight or volume) accuratly, you can assume that a 2:1 by weight or volume will work.
I originally posted because I couldn't find the density in the manufactures data, Vic very kindly found that for me.
Click to expand...
I think you have misunderstood what Philippe is suggesting

He is saying mix 100g of part A with 48.6g of part B

That is 93.45 cc and 46.73cc respectively which is precisely 2:1
 
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