Does paint affect the thermal conductivity of a metal? We noticed that in our experiment that painting a metal increases its thermal conductivity; is this true? If so, can you guys send me a link to a research paper to support this claim.
 A: 
painting a metal increases its thermal conductivity; is this true?

No it is not true. 
Thermal conductivity is a bulk property of the material. It expresses how well the metal conducts thermal energy through the bulk of an object made of that metal.
As CuriousOne commented, surface treatments do not affect how heat is conducted in the interior of the object - they can affect emissivity. 
A: In regard to the color of the paint or just the paint itself? Because if you are referring to the color applied to a metal then you don't really need a paper to prove that anymore. Its a old idea. Black or darker colors have a higher thermal conductivity because more colors are being absorbed. Lighter colors (like white) have more colors that they are emitting so they have less thermal conductivity.  
A: It is trivially true because you are adding more material. So you have the original conductivity of the metal plus the conductivity of the paint. Additionally, the paint will reduce heat transfer away from the metal by convection etc.
Of course, this only applies if you are measuring conductivity from one part of the metal to another, and not measuring between metal and the other side of the paint.
A: In my profession we look at heart conductivity of a system in terms of thermal resistance.   You can look at thermal resistance in terms of Ohm's law; hence adding paint in terms of this transformational analysis results in the thermal resistance of the metal in series with the thermal resistance of the paint.  If you only consider the thermal differential between the unpainted side of the metal and the other side where the paint is exposed, the total thermal between those 2 surfaces is the summation of the two thermal resistance. Higher thermal resistance will result in lower thermal conductivity from one side to the other.
