Dispensing 2k paint?

[bigegg]

In your 150g example above, assuming that is paint - how do you work out how much hardener?

It will (sometimes) say in the TDS.

If it's (say) 3:1 paint:hardener by weight, then it's ( (paint weight) x 1) ÷ 3 of hardener by weight.

If it's 75% paint : 25% hardener, then it's
(25 X paint weight) ÷ 75 of hardener.


For Hempadur 45143, it's 5.4:1 by weight, 3:1 by volume.

 

[Kram]

Guys I have bad news for you.

For those saying to use Salter / Kitchen digital scales to measure paint:

View attachment 537568

What I have also experienced first hand myself with our 2x modern digital kitchen scales is:

Weighing bags of coins. Way off! If I had equal bags of 5p coins weight wise on the digital scales, they were all not right and sometimes varied up to + / - 10 coins per bag!

Weighing small parcels. When I get to post office and use their accurate scales, they were off by a fair bit too.

Short of it is - they are not designed for paint measurements. I would not trust them for that.

Just use paint cups for their intended puspose. If you are off a mm or 2 on the scale it will still be in the right ball park. Kitchen scales will likely be off by much more and you may never know.

Pro paint shops using proper digital scales - 100%. Kitchen scales - bad idea IMO.

Wrong your screenshot answer is talking about colour mixing to a scheme where small amounts can affect the colour, not 2 part primers and clears.

Drug dealer/jewlers scales have 0.01g precision and are more accurate than I can check. 200g limit, they are perfect for paint measuring, sometimes a bit too sensitive.

For larger quantities I weigh the hardener first then swap to kitchen scales which are good to the nearest gram which is better than you'd get it by eye with a cup, and perfectly fine for the larger quantities.


For the small trim panel I did the other day, if I were doing that on its on, it would only need 30ml of clear, and they dont do paint specific mixing cups that small.

While paint still works if you get the ratios wrong, it may mean it doesnt cure quite as hard or fast as it was designed go be.


I also weigh body filler, and hardener on the jewlers scales. Last time I needed 0.06g which is a small pea size. I hate the stuff

 

[Turbo]

Guys I have bad news for you.

For those saying to use Salter / Kitchen digital scales to measure paint:

View attachment 537568

What I have also experienced first hand myself with our 2x modern digital kitchen scales is:

Weighing bags of coins. Way off! If I had equal bags of 5p coins weight wise on the digital scales, they were all not right and sometimes varied up to + / - 10 coins per bag!

Weighing small parcels. When I get to post office and use their accurate scales, they were off by a fair bit too.

Short of it is - they are not designed for paint measurements. I would not trust them for that.

Just use paint cups for their intended puspose. If you are off a mm or 2 on the scale it will still be in the right ball park. Kitchen scales will likely be off by much more and you may never know.

Pro paint shops using proper digital scales - 100%. Kitchen scales - bad idea IMO.

I'm not mixing up colours or tints, the paint shop has already done that on their super accurate scales.

I'm just adding hardener and thinners and as others have said it doesn't need to be super accurate for it to work.

When you are mixing body filler do you weigh or measure the ratios? It's done by eye and if you are slightly out it will still harden either slightly slower or faster.

I have compared my scales to the post office ones and they are always spot on. Maybe you need to get a more accurate set of scales?

 

[JOEPRO]

The paint and hardener have different densities, I'm pretty sure volume is 2:1 and weight is 10:3 for lechler epoxy but always check data sheets.

It will (sometimes) say in the TDS.

If it's (say) 3:1 paint:hardener by weight, then it's ( (paint weight) x 1) ÷ 3 of hardener by weight.

If it's 75% paint : 25% hardener, then it's
(25 X paint weight) ÷ 75 of hardener.


For Hempadur 45143, it's 5.4:1 by weight, 3:1 by volume.

These statements conflict do they not?

Is it not by volume OR if by weight then you need the data sheets to provide that weight ratio?

Paint and hardener are different densities by volume?

 

[JOEPRO]

I'm not mixing up colours or tints, the paint shop has already done that on their super accurate scales.

I'm just adding hardener and thinners and as others have said it doesn't need to be super accurate for it to work.

When you are mixing body filler do you weigh or measure the ratios? It's done by eye and if you are slightly out it will still harden either slightly slower or faster.

I have compared my scales to the post office ones and they are always spot on. Maybe you need to get a more accurate set of scales?

What model of Salter scales do you have Turbo? Sounds like me needs a set

 

[bigegg]

These statements conflict do they not?

Is it not by volume OR if by weight then you need the data sheets to provide that weight ratio?

Paint and hardener are different densities by volume?

It depends upon the brand - some epoxies are 50/50, some are 5:1 (for resins, at least, and by weight)

Lechler paint is 2:1 by volume. Hempel is 3:1 by volume

The TDS for the particular brand gives the correct ratios - sometimes by volume, sometimes by weight. Sometimes by both.
Sometimes one, or both ratios, are also on the label.


The densities of the paint and hardener _are_ different, so the ratio by volume will be different to the ratio by weight.

 

[Kram]

Is it not by volume OR if by weight then you need the data sheets to provide that weight ratio?

Paint and hardener are different densities by volume?

Its not usually in the TDS which is a great annoyance. Tip the whole new tin into an accurate clean measuring beaker and weigh it to work out the density and write it on the tin for future use, tip it all back...

Hb body 989 is 1.69g/cm3 with the hardener 0.89g/cm3. My 2k thinners is 0.92g/cm3, as an example.
I write on the tin 169g to 22.25g which accounts for the density and ratio.
The tin has a large area for foriegn languages which is a good space to write the weights for various measurements..

 

[julianf]

In your 150g example above, assuming that is paint - how do you work out how much hardener?

If I'm spraying epoxy, it's 30g per 100g, so, say, I've tipped out 86.37g of epoxy, it would be...

0.8637x30 to give me the weight of hardener required.



If I'm spraying a single stage top coat, that is 50g per 100g, so my 86.37 would require 43.185g of harder (86.37 / 2)

(Obviously if you wanted to do the sum in the same way as the epoxy it would be 0.8637 x 50, but it would give the same answer)

If I then wanted to add 15% (of the total weight) thinner, id still have the 43.185 on my calculator, so I'd times it by 3 to get the total weight, and then times that by 0.15.

Or 0.2 if I wanted 20%
Or 0.1 if I wanted 10%

(I do change the thinner quantities, as a lot of my work has intentional peel on it, so as to show finger prints less - it's not car stuff)


High build is different numbers again, but I can't remember them off the top of my head, but the sums are the same form.


I weigh up in a mixing cup with graduations on the side, but never use them. I frequently mix small volumes of paint (50g to 200g quantities) and at 50g, I think the graduations on the cup would give quite a high potential percentage error.

 

[Kram]

If I'm spraying epoxy, it's 30g per 100g, so, say, I've tipped out 86.37g of epoxy, it would be...

0.8637x30 to give me the weight of hardener required.



If I'm spraying a single stage top coat, that is 50g per 100g, so my 86.37 would require 43.185g of harder (86.37 / 2)

(Obviously if you wanted to do the sum in the same way as the epoxy it would be 0.8637 x 50, but it would give the same answer)

If I then wanted to add 15% (of the total weight) thinner, id still have the 43.185 on my calculator, so I'd times it by 3 to get the total weight, and then times that by 0.15.

Or 0.2 if I wanted 20%
Or 0.1 if I wanted 10%

(I do change the thinner quantities, as a lot of my work has intentional peel on it, so as to show finger prints less - it's not car stuff)


High build is different numbers again, but I can't remember them off the top of my head, but the sums are the same form.


I weigh up in a mixing cup with graduations on the side, but never use them. I frequently mix small volumes of paint (50g to 200g quantities) and at 50g, I think the graduations on the cup would give quite a high potential percentage error.

I dont know what paint your using but those numbers seem way off for the epoxy.

Your top coat calcs assume each part has the same density, which they do not, although I admit it is close with some of them.