Finishing in Winter, Unheated Garage

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Forum topic by jmartel posted 11-14-2014 05:03 PM 4454 views 0 times favorited 19 replies Add to Favorites Watch
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9223 posts in 3360 days

11-14-2014 05:03 PM

So, my shop is in my unheated undersized 2 car garage. While the winters here aren’t as bad as say in Montana or North Dakota, my garage does get down into the 40’s or so in there. Obviously, this is not ideal for finishing.

What I was thinking of doing as a solution was to make a knock-down heated booth out of PVC and plastic drop cloths. Make it large enough to fit whatever it is I need to fit in there, say a 4×6x7 cube. That way I could direct a space heater into an opening to keep the temperature more in the 60-70 ideal range. I won’t be spraying any finishes, just things like Arm-R-Seal, Shellac, Danish Oil, etc.

Does anyone forsee any problems with this idea?

I’m also looking into insulating the garage door as well.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

19 replies so far

View Mark Kornell's profile

Mark Kornell

1171 posts in 3741 days

#1 posted 11-14-2014 05:20 PM

The plastic spray booth doesn’t hold heat well. A small space heater inside will warm up the box reasonably well, but it will lose most of its heat within a few minutes of shutting off the heater. If you’re OK with leaving the heater on for a couple hours after applying a finish, it might work out.

-- Mark Kornell, Kornell Wood Design

View jmartel's profile


9223 posts in 3360 days

#2 posted 11-14-2014 05:32 PM

Yeah, that was the plan was to leave the heater on or cycle it on/off to keep the temp up.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View mahdee's profile


4291 posts in 2977 days

#3 posted 11-14-2014 05:43 PM

I would avoid force air heaters with the heating coils exposed. If that was all I had, I would duct the heater into the room.


View john2005's profile


1768 posts in 3388 days

#4 posted 11-14-2014 11:04 PM

I believe you are after an infrared heater jmart. May be worth looking into at least

-- In theory there is no difference between theory and practice. In practice there is.

View JAAune's profile


2003 posts in 3527 days

#5 posted 11-14-2014 11:07 PM

If you can get the temperature of the working area up to 50 degrees, it’s possible to brush shellac if the shellac is kept warm inside a container of hot water. I once completed a time-sensitive project by getting hot water from the tap and setting my jar of shellac inside that while I brushed the topcoat on. It took a couple trips for more hot water but did eliminate blushing issues.

I’ve known one person to use a coffee cup warmer to accomplish the same.

-- See my work at

View TheWoodenOyster's profile


1335 posts in 3145 days

#6 posted 11-15-2014 01:00 AM

Man… I remember when winter used to hit here in Texas about halfway thru December. It got cold a week ago here. What the heck? What happened to Texas being hot?

I know, I know, you guys from the north are laughing. But hey, put me in front of a blast furnace and I’ll savor every minute…

I’m going to be running into the same finishing issue soon as well. I want to try my first rattlecan lacquer finish, but not in this weather. I thought I would have til the end of November at least, but it’s already getting into the 20’s.

-- The Wood Is Your Oyster

View Woodmaster1's profile


1851 posts in 3797 days

#7 posted 11-15-2014 02:29 AM

I have a 50,000 BTu natural gas garage heat that does a great job. I has gotten down to 22 degrees and the garage stays at 55 where it is set. The garage is 33×30 with 9’ ceiling.

View jmartel's profile


9223 posts in 3360 days

#8 posted 11-15-2014 02:31 AM

I’m not looking to buy a big unit to heat the whole garage. I don’t plan on staying in this house more than another 5 years or so. When I move I plan on building an insulated and heated shop. I’m just looking for a solution for the short term.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View Jim Finn's profile

Jim Finn

2898 posts in 4132 days

#9 posted 11-15-2014 12:59 PM

Even in the summer I heat rattle cans of finish or paint, in a coffee can of hot water, for ten minutes. Makes for a nice fine mist while spraying.

-- No PHD just a DD214 Lubbock Texas

View Blackie_'s profile


4883 posts in 3722 days

#10 posted 11-15-2014 02:13 PM

I’m in central TX and have a 10’ x 8’ metal storage shed in the back yard, those kind you get from HD, I set up a work bench in it and use an 1500 watt Stanley heater which seems to do the trick in there.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at

View john2005's profile


1768 posts in 3388 days

#11 posted 11-18-2014 09:12 PM

Doode, look up infrared heaters. Then buy one. Then take it with you to your new home. win win win.

-- In theory there is no difference between theory and practice. In practice there is.

View TomB19's profile


52 posts in 3178 days

#12 posted 11-25-2014 11:15 PM

I know I’m late to this party but I live in Saskatchewan, Canada. We may not have invented winter but we have certainly perfected it. It’s amazing what can be done with a heat lamp or two. I’m talking about a reflector fixture with a clamp on mount and a plain old 250W heat lamp.

The key si to point the lamps at the object to be finished, prior to applying the finish. The heat path will be extremely focused. It won’t heat the shop much but it will certainly keep your project toasty. In fact, you have to be careful not to overheat the item in question.

You can also heat things from the inside. For example, a dresser can be warmed with a couple of hook lights. Spin in the largest incandescent lamp that will safely work and put the hook light inside the dresser about 15 minutes prior to finish application.

Surface temperature is easily tested with an IR thermometer. They are cheaply available.

I know it’s not like having a heated shop but I’ve done a ton of work, including temperature sensitive polyurethanes and polyester resin based FRP, in unheated shops on nice days in winter.

View TomB19's profile


52 posts in 3178 days

#13 posted 11-25-2014 11:19 PM

We just moved to a house that has an unheated garage so I use a kerosene construction heater (I actually run diesel so it stinks a wee bit but not too bad once adjusted properly).

Remember, the concrete slab ways many tons. The air is light. If you turn on a heater for a few minutes, you can heat the air but that heat will be absorbed into dozens of tons of cold objects, shortly after you turn off the heat source. The longer you keep the shop warm, the longer it will stay warm. Once you get the slab, building, and contents warm, it will stay warm for a long time. Mine will stay above freezing for about a week, even in 40 below weather, but only if I keep it at 70F for two days prior to killing the heat.

View Bill White's profile

Bill White

5357 posts in 5170 days

#14 posted 11-25-2014 11:47 PM

Look at oil filled elec. radiators. No flame, no odor, has thermostat, inexpensive, and idiot proof.
That’s what I use ‘cause I’m an _ (fill in the blank). Oh well.

-- [email protected]

View Purrmaster's profile


915 posts in 3303 days

#15 posted 11-26-2014 08:19 AM

If you can heat your shop or your finishing space, that’s a good idea.

Two points to keep in mind:

1.) You can do finishing in the cold. Oil based varnishes and shellac will still cure/dry. But they will take much longer. I’ve also had reasonably good luck brushing lacquer in the freezing cold (note I said brushing, not spraying). Once again, it will take much longer to dry. Water base finishes and oils like BLO and danish oil never worked for me below around 60 degrees.

2.) Oil based finishes like poly and Waterlox cure by reaction with oxygen. So make sure there is enough air circulation so they don’t get oxygen starved.

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