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Old 10-31-2017, 02:36 AM   #1
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Default Covering in winter?

I did some searching through existing threads, but didn't find any mention of how folks do covering in winter (except on on the min temp for Stewart Systems, but I'm using Stitts). Due to a bunch of poor planning and execution on my part, I didn't get any fabric work done this summer. Now it's getting cold, and I really don't want to just stack arms again like I did last winter.

Does everybody north of the Mason-Dixon line just not spray Poly-Spray between October and May? Is it practical to warm up the shop, turn off the heat, spray the finish, and turn the heat back on the next day? Can a simple plastic enclosure be used inside the shop with an exhaust to create a negative pressure to keep the fumes away from the heater? Do HVLP guns reduce the fumes significantly? Can I at least get away with doing the Poly-Brush coats?


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Old 10-31-2017, 04:10 AM   #2
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Cold weather makes glossy paint and keeps blushing down. Does make it easier to run it though. Depends on the heater, but i would warm everything up, paint and leave for a while. Turn on the heater after some venting, and let it dry the rest. It just will be slow going. If I was at that step, it would not stop me. Bigger problem is really heating it up. You will probably have to bring in extra heaters and get the temp up as once you shut them down, the clock is ticking to get done before it gets cold in there. Depends on shop; depends on the heat.

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Old 10-31-2017, 12:44 PM   #3
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I did some of this last winter. I have a wedding tent inside my steel building as a spray booth. When its cold, the issue is running the fans. Its cold again in a moment. The ticket would be if you can push filtered warm air into the booth from a remote heater. I thought about calling my HVAC repairman to keep an eye out for a cheap forced air unit someone has let go.

To more directly answer your question, I heated the booth with propane, killed the heat, sprayed the polyspray with no fans and a supplied respirator, ran the fans long enough to clear the cloud, then set a couple of electric heaters in to warm things up.

This year i considered using a tarp off the sides of the spray booth to make a lean-to. I thought i could heat the lean-to surrounding the tent/booth with warm air without exposing the fumes to an ignition source. So far, i've just sat on the couch since the snow fell.
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Old 10-31-2017, 01:05 PM   #4
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Originally Posted by TFF1 View Post
Cold weather makes glossy paint and keeps blushing down. Does make it easier to run it though.
Correct, cold weather keeps blushing down.
In general, when it's cold there is less water in the air.

A product like PolyTone (Stits dope) evaporates relatively quickly. As this happens you get evaporative cooling. So the painted object cools down as the solvent evaporates.

Try a little MEK or Acetone on the back of your hand and then blow at it to make it dry. It feels cold.

Take a soda can out of the fridge, in humid weather water beads on the can.

So in humid days, cooling of the surface attracts water.
Water molecules get into the surface of the paint and causes interference with the top layer = low gloss/sheen or blushing.

The faster the thinner/solvent you add the colder the object gets.
PolyFiber has slower thinner and or retarder to use in the paint to slow down the evaporation = not as cold during evaporation = less chance of blushing.

Now lets say it's winter (humidity is low) It's cold so you heat up the shop to say 70 degrees. = Ideal. The solvent will evaporate quickly because there is more room in the air (not saturated with water) = consider a slow thinner to get the best flow and leveling, and also less overspray melt in.

Same scenario. But you have no heat, therefore the spraying and drying conditions will be 45 to 50 degrees = (anything lower, don't spray) So it's 45 to 50 degrees. This time the solvent evaporates very slowly because the air and the object temperature is cold.
The paint's initial drying qualities are not good. Chances are there will be flow indicators or paint runs.
Do you use Fast thinner for a big job? (our stuff is big) I would probably use a combination of solvents because the job is a wing for example. and allow a long time between coats for the solvent to rid itself from the previous coat.

As with any climate extremes you fighting a battle. When the air, object and paint is cold. Or when the air, object and paint is very warm. Now add the humidity of say Louisiana. That is another battle.

Imagine a cold object that is going to be painted. Then you spray paint, that is going to evaporate and cool the object even further, you are now way below 45 to 50 degrees. The paint applied gets thicker and real slow flash off. This is what causes orange peel and paint runs for example.

If you have one of those infra red heat seeking thermometer guns you can see this happening.

Cold paint is thicker viscosity than warm paint. Consider adding a little more thinner (maybe 5 to 10% more) to bring the viscosity down for those cold days

Note: Generally speaking, a urethane has much less chance of blushing because inherently the solvent evaporate slowly. Try a little reducer on the back of your hand and blow at it = no change in temperature. Make sure it's the reducer and not the hardener.

Waterborne, Your kind of stuck because the solvent is water (only one speed) I would enquire with the manufacturer is there are any additives.
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Old 11-02-2017, 08:32 PM   #5
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As with any climate extremes you fighting a battle. When the air, object and paint is cold. Or when the air, object and paint is very warm. Now add the humidity of say Louisiana. That is another battle.

Yeah, tell me about it.
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Old 11-02-2017, 09:12 PM   #6
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Default Heat

If you have a makeshift paint booth inside a building, create a small tunnel from the booth to outside the building. Put a big propane heater outside the building at the end of the tunnel. Exhaust air on the opposite end of the booth from the heater duct. For components the sixe of a S2 or Skybolt lower wing, use a fresh air breathing system and you will be able to paint one side, then turn exhaust fan on for a few minutes.
If spraying dope, lots of retarder.

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