"Baking" Future?

[dneid]

Hey, All,
Had this pop up when reading Paul's post about putting a plane under a warm lamp to clear up any clouding in future. Has anyone tried the idea of "baking" future under a lamp to speed the curing process? I tried it with a scrap model. I sprayed the Future on last night and sat the scrap under a painter's utility lamp with a 75 watt incandescent bulb. I checked the temp with a back of the hand feel and let it sit under the lamp for about 4 hours. I then applied a couple of decals and all seemed fine. Just curious if anyone else has tried this.

Dale

 

[meatloaf109]

Yes, I regularly speed up drying time with my desk lamp. But be careful, sometimes the bottom won't be as dry as the top.

 

[Vic Balshaw]

That's a new one on me but with the relatively mild to hot and dry climate we have, drying is not usually a problem, in fact sometimes it's too damned quick.

 

[meatloaf109]

I had to start that years ago, The humidity here is awful. We got a heavy wet snow today, by monday it is supposed to be 57 and raining.

 

[Crimea_River]

Not tried that. I prefer to let it take its own sweet time.

 

[Wayne Little]

Yeah me too....

 

[Airframes]

And me. Artificial heating can possibly harden the top 'layer;, but leave the 'underside' still soft, which could cause crazing or 'orange peel' once the Future has fully cured naturally.

 

[meatloaf109]

I've not had a problem with that, not yet, anyways. I tend to be a bit conservative with the spraying of the future mostly because of the danged rain forrest that is Western North Carolina. More heavy wet snow this morning, changed over to rain again.

 

[mikewint]

Afew posts have mentioned "drying". Acrylics dry as the vehicle that carries them, mostly composed of water, leaves the film. As water evaporates or is absorbed by the substrate, tiny acrylic polymer spheres are forced into ever closer contact. Eventually they are crowded so tightly that the spaces between them create capillary forces, and water is pulled from the paint film. This capillary action packs the acrylic spheres against one another in a honeycomb-like pattern, and they begin to form a continuous, cohesive film. As this occurs, the polymer spheres, composed of long chains of acrylic, actually deform and partially combine with one another in a process of film formation called coalescence.

Thus the "drying" of acrylic paints occurs in two very different stages and drying times must be thought of in two different time frames. The first stage, a relatively short period of time, results in the formation of a skin over the surface of the paint. This is the time that it takes for acrylics to "dry to the touch". At this point, the flow of water towards the surface is no longer sufficient to keep the paint film wet. Very thin films can feel dry within seconds, while thick films may take a full day or more to skin over.

The second stage of drying is the time for the entire thickness of the film to be thoroughly dry. That is, the time required for all of the water and solvent to evaporate and leave the film. This is a most crucial time frame, as the ultimate physical properties, such as adhesion, hardness and clarity, do not fully develop until the film is near complete dryness. For very thin films, this time may be a few days, while films of 1/4 inch thickness or more will take months and even years to be completely dry.

Both the evaporation rate of the water/solvent and the chemical bonding rate of the acrylic polymer spheres depend on temperature and humidity. Ideally, the temperature should be around 70 to 90F(21C to 32C) during the drying/curing process. Temperatures below 49F (9C) will not allow the polymer solids to properly coalesce to form a continuous film, and may result in film failure (cracking, adhesion failure, powdered film, etc.). Higher temperatures, like those reached with a hair drier or heat lamp, can speed drying times up significantly, but overheating can cause bubbling or burn the acrylic film. Likewise, lower temperatures will slow down the drying process and can be used to one's advantage for increasing the working time of the acrylic paints.
Relative humidity in excess of 75% will slow the evaporation of water from the surface, slowing down the drying process. Temperatures of 70 to 85F(21C to 29C) and humidity under 75% are ideal for drying. So unless your work area is cold and damp extra heat is unecessary but you can use a gentle heat to 85F if you wish

 

[dneid]

Hey, Mike,
GREAT info! Makes me rethink the whole acrylic idea. Need to experiment and find what I like.
Dale

 

[N4521U]

And I understood that.......... that's amaaaaazing.

Thanks for that. When I was sign painting in the States, long ago, we used to do a "coat and a half". Applied the second coat when the first was dry "to the touch". Worked well on a cold vertical concrete wall we couldn't possibly return to. For reds, made the color last longer as well. Using enamels we would use lacquer thinner on the first coat, to prevent the paint from running, evaporation time. Then the second would be using mineral spirits so as Not to make the first coat run.

 

[mikewint]

Personal opinion: For the home modeler without special equipment acrylics cannot be beat. Water clean up with perhaps a bit of isopropyl alcohol, no fumes to speak of, toxicity essentially zero, non-flamable, non-explosive, drying time easily controled through humidity and temperature.