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Weight gain from paint - data point

McFly

Well Known Member
I thought there was a specific thread devoted to this. If there is I could not find it.

I was under the impression that a RV paint job added up to 50 lbs (yikes!)

My naked RV-7 without wheel pants, leg fairings and intersection fairings weighed 1034. Now painted and with all of the parts it weighs 1055. So it only porked up 21 pounds :) I'll guess at least five of those pounds were from the fairings. So I'll say my paint weighs 16 pounds give or take.

So I am curious. For those who have personally been through this, how much did your paint job really weigh?
 
I just weighed a gallon of paint. It came in slightly over seven pounds. Take off a pound and "slightly", for the can, to end up with six lbs. per gallon.

Using roughly two gallon cans of paint, almost a gallon can of primer, and a quart or two for trim; I can easily see an addition of sixteen lbs. or so, when you account for overspray zipping through the exaust fans.

I orignally bought three gallons of paint, but have one+ left, in addition to a qt. of black & white for striping.

L.Adamson

edit: had to add a bit over 5 oz. of lead, to balance the elevators after painting.
 
hmmm

tomcostanza said:
But a lot of that is solvent. Only the weight of the solids contribute to the weight of the plane.
wouldnt most of the solvents be in reducers or catylists (sp) but the unmixed paint be mostly solids. i know there is some solvents or it wouldnt be a liquid.
 
Last edited:
VOC's

Check the paint container and somewhere it should tell you the % of VOC's (volitile organic compounds). This ( I think) is the amount of solvents, as mentioned above, that evaporates into the atmosphere. The difference is what is left behind as solids (paint) on your plane. I may stand corrected...but I think it will be close to actual weight.
 
When I was painting my dad's old '82 Harley Sporster a few years back I downloaded the DuPont ChromaClear Technical Manual and had it handy in the computer. An excerpt is below. Now granted, this is just the clearcoat that goes on top of the color base coat.

>Physical Properties
>VOC: 4.2 lbs/gal ready-to-spray.
>Theoretical Coverage: 496 sq. ft. per ready-to-spray gallon at 1 mil.
>Weight Solids: 37.5% ready-to-spray.
>Volume Solids: 30.4% ready-to-spray.
>Recommended Dry Film Thickness: 2.0 - 2.4 mils in 2 coats.
>Flash Point: See MSDS.

I guess what I'd point out is that it weighs 4.2 pounds per gallon. And only 37.5% of that 4.2 pounds, or 1.6 pounds per gal is solids--the rest evaporates.

1 gal is theoretically supposed to cover 496 sq ft and if a wing is 32' x 5', that's 160 sq ft. Double it for the top and bottom, now we're up to 320 sq ft. Take 320/496*1.6 and that equals 1.03 pounds--not a lot. Of course this doesn't accout for the primer, fill-n-sand, and base coat.

So what does it all mean? Heck, I don't know. I guess it means, if you paint your airplane, it's going to weigh more.

Best,

-Jim
 
Don't forget that only about 70% (if you're good) of that gallon actually lands on the intended target.
 
Paint weight gain data point.

Well 9.5 years ago, my airplane was painted with Dupont ChromaOne over Dupont VeriPrime.

Using the same CALIBRATED electronic scales, my airplane gained eight (8) pounds after painting.
 
fehdxl said:
When I was painting my dad's old '82 Harley Sporster a few years back I downloaded the DuPont ChromaClear Technical Manual and had it handy in the computer. An excerpt is below. Now granted, this is just the clearcoat that goes on top of the color base coat.

>Physical Properties
>VOC: 4.2 lbs/gal ready-to-spray.
>Theoretical Coverage: 496 sq. ft. per ready-to-spray gallon at 1 mil.
>Weight Solids: 37.5% ready-to-spray.
>Volume Solids: 30.4% ready-to-spray.
>Recommended Dry Film Thickness: 2.0 - 2.4 mils in 2 coats.
>Flash Point: See MSDS.

I guess what I'd point out is that it weighs 4.2 pounds per gallon. And only 37.5% of that 4.2 pounds, or 1.6 pounds per gal is solids--the rest evaporates.

1 gal is theoretically supposed to cover 496 sq ft and if a wing is 32' x 5', that's 160 sq ft. Double it for the top and bottom, now we're up to 320 sq ft. Take 320/496*1.6 and that equals 1.03 pounds--not a lot. Of course this doesn't accout for the primer, fill-n-sand, and base coat.

So what does it all mean? Heck, I don't know. I guess it means, if you paint your airplane, it's going to weigh more.

Best,

-Jim
I think you have a math error. Paint ready to spray is much heavier than 4.2 lbs (gas weights 6 lbs/gal and has no solids in it; at least at my airport). The 4.2 lb/gal is the part of the paint that flashes off (evaporates) which by my calculations from your example should be (100%-37.5%-30.4%) 32.1% of the ready to spray mixture. Therefore a gallon ready to spray should weigh 13.1 lbs. Of coarse this is all correct if you actually use the prescribe amount of reducer.
 
Good point. Actually, the 30.4% number is a volume, not weight. So if the VOC (Volatile Organic Content ?) is the part that evaporates, then 4.2 pounds divided by the total weight = 37.5%. Total weight must be 11.2 pounds. That leaves 7.0 pounds per gal as solids left on the plane. Close enough ballpark figure for a 'tractor going to Denver, not Mars', as someone once said. Thanks. -Jim
 
fehdxl said:
Good point. Actually, the 30.4% number is a volume, not weight. So if the VOC (Volatile Organic Content ?) is the part that evaporates, then 4.2 pounds divided by the total weight = 37.5%. Total weight must be 11.2 pounds. That leaves 7.0 pounds per gal as solids left on the plane. Close enough ballpark figure for a 'tractor going to Denver, not Mars', as someone once said. Thanks. -Jim
OK,
I'm going to beat the poor old horse one more time.

If the part that evaporates is 4.2 pounds (the Volatile Organic Compounds) and the part that stays behind (the solids) weighs 37.5% of the total, then the VOC's weigh 62.5% of the total (100% - 37.5%).

Then total weight in this example must therefore be 4.2/.625 = 6.72 pounds.

Solids are 37.5% of 6.72 pounds and should be 2.52 pounds.

This assumes that the only evaporating constituents in the clear coat are VOC's, of course and the total weight is made up of only the solids and the VOC's.

-Mike
 
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