How much will dehydronators reduce dry times

[69NovaYenko]

Back in 2007 a competing car modeling forum suggested some air dry times for various  paints:

Lacquer:10-20 minutes

Acrylic: 1-2 Hours

Enamel: 24 Hours

However, if you drop you parts in a dehydrator how much would it reduce dry time in general. Of course this would be a guesstimate  because the temp you set the unit to has to be factored into the final answer.

[StevenGuthmiller]

24 hours for enamel is a pipe dream!

Maybe to the touch, but not cured.

I stopped using enamels years ago because I got tired of waiting 3 months for it to totally cure.

Even lacquers require more time than this to cure to the point of being ready for polishing and such.

I don't use a dehydrator....don't need one.

If you're using lacquer, just be a tiny bit patient and give it a couple of days after the final coat to cure.

If you're using enamel, switch to lacquer!

 

 

 

Steve

[MrObsessive]

To be just a bit contrary, I had enamel (Humbrol) paint dry in the dehydrator overnight without any 'tackiness' whatsoever. Sometimes there are certain interior hues that you just don't have on hand but in an enamel and you have to use whatcha got.

Another example is Tamiya's Acrylic Clear X-22. That stuff to me dries at a snails pace, but in the dehydrator overnight, it dries rock hard. One caveat though is to not put it in there immediately. Doing so can make it yellow a bit in spots particularly on sections where the paint is built up along body creases for instance. I might wait about an hour to let it setup before putting it in the dehydrator.

BTW, I gotta give whoever made my dehydrator a LOT of credit (Nesco)! I've had the same one since 1996 and it still works well. It's thermostat controlled and I've had nary an issue with it in all these years.

[Dave G.]

You can dry pretty much to a cured finish Testors or MM enamels in 6 hours in a dehydrator. I don't do that, I go 3 hours @ 109 deg, then let it sit till I'm ready for it. I just want it so I can handle it and not do damage, 3 hours is more than enough for that.. Since the body is more or less the first thing I get painted ( at least the base color coat) it's going to be days till I get back to it anyway.

Acrylics will not dry in a single day, not by air drying, it's more like two to three days depending on the weather. You can reduce that to an hour in a dehydrator.

I agree that lacquer to cure takes a couple of days at least, two hours in the dehydrator will do lacquer quite well.

When a paint is cured there is no more odor in a good old fashioned sniff test ( even acrylics have some out gassing). Place item up to your nostrils and take a short whiff, there should be basically no odor. Find a little corner to push your finger nail into, it should leave no dent in the paint.

By the way one thing some folks rush and it's the foundation to the whole paint job is the primer coat. Give that the same times as above.

My dehydrator is my wife's air fryer lol. It has all these modes to which one is dehydrate, it's thermostatic controlled. It has bake modes, air fry modes, toaster oven modes, you name it. Last night I cooked pizza in it, last week my wife did a roast in it. A few days ago I dehydrated acrylic paint, a few weeks ago enamel.

Edited May 4, 2019 by Dave G.

[Foxer]

30 minutes ago, Dave G. said:

My dehydrator is my wife's air fryer lol. It has all these modes to which one is dehydrate, it's thermostatic controlled. It has bake modes, air fry modes, toaster oven modes, you name it. Last night I cooked pizza in it, last week my wife did a roast in it. A few days ago I dehydrated acrylic paint, a few weeks ago enamel.

You sure have a loving wife!!   ))

[TarheelRick]

1 hour ago, Dave G. said:

My dehydrator is my wife's air fryer lol. It has all these modes to which one is dehydrate, it's thermostatic controlled. It has bake modes, air fry modes, toaster oven modes, you name it. Last night I cooked pizza in it, last week my wife did a roast in it. A few days ago I dehydrated acrylic paint, a few weeks ago enamel.

Hmmm, I wonder what an air-fried model would look like.  Not really sure I would want to use a kitchen utensil I use for cooking to dry model paints with.  But if it works who am I to question.

[NOBLNG]

1 hour ago, Dave G. said:

When a paint is cured there is no more odor in a good old fashioned sniff test

My dehydrator is my wife's air fryer lol. It has all these modes to which one is dehydrate, it's thermostatic controlled. It has bake modes, air fry modes, toaster oven modes, you name it. Last night I cooked pizza in it, last week my wife did a roast in it. A few days ago I dehydrated acrylic paint, a few weeks ago enamel.

So when your model no longer smells like roast beef it's dry!

[Dave G.]

3 hours ago, TarheelRick said:

Hmmm, I wonder what an air-fried model would look like.  Not really sure I would want to use a kitchen utensil I use for cooking to dry model paints with.  But if it works who am I to question.

I don't know, it works great though . I'd agree with you if I used it as a spray booth but there is no residue left behind. The pizza was good last night by the way !

[Dave G.]

4 hours ago, Foxer said:

You sure have a loving wife!!   ))

She's pretty special indeed.

[StevenGuthmiller]

13 hours ago, MrObsessive said:

To be just a bit contrary, I had enamel (Humbrol) paint dry in the dehydrator overnight without any 'tackiness' whatsoever. Sometimes there are certain interior hues that you just don't have on hand but in an enamel and you have to use whatcha got.

Another example is Tamiya's Acrylic Clear X-22. That stuff to me dries at a snails pace, but in the dehydrator overnight, it dries rock hard. One caveat though is to not put it in there immediately. Doing so can make it yellow a bit in spots particularly on sections where the paint is built up along body creases for instance. I might wait about an hour to let it setup before putting it in the dehydrator.

BTW, I gotta give whoever made my dehydrator a LOT of credit (Nesco)! I've had the same one since 1996 and it still works well. It's thermostat controlled and I've had nary an issue with it in all these years.

You're right Bill, I should have been more specific in my statement about enamels by stating that I was referring to good old fashioned Testors gloss enamel spray paint.

The flat enamels, of course, dry much faster.

I can't really attest to how fast the bottled gloss enamels dry because I use very few of them, and when I do, it's usually from an airbrush thinned with lacquer thinner.

I guess I've just never felt the need to have to rush things along with a dehydrator.

I've never been in that much of a hurry and mother nature does just fine by me.

Who knows, maybe some day I will change my mind.

 

 

Steve

[Pete J.]

Ok, I'm going to add a little piece about enamels.  After some research, the only way to speed up enamels is to use UV light.  They cure rather than dry.  I always get a chuckle out of people who say they painted something with enamel and put it in a box to keep the dust off and then wondered why it was still tacky months later.  By keeping UV light off of it they are actually making the problem worse.   If you put it outside in direct sunlight it will speed the process or you can get a UV light to put it under.  Personally I have not done this as I don't use enamels that frequently to justify it, but a UV bulb would not be all that expensive. 

As to the food dehydrator, I wouldn't paint without it. I use it for two purposes.  First, I store my rattle cans in it to keep the paint warm.  The internal temperature is not sufficient to cause any issued with burst cans and this way the cans are ready to every time. Second, I paint with lacquers and it definitely cuts down the curing times. 5 to 10 minutes to flash off the lacquer so it is ready to recoat.  Then when the final coat is down, overnight for a final cure.  Definitely speeds up the process.  If I lay down thin coats, I can cut and buff in under two hours.  

The heat also is great for accelerating the curing of two part fillers. 

Oh, and the temperature is low enough that I don't need to worry about warping plastic or most resins. 

[MrObsessive]

35 minutes ago, StevenGuthmiller said:

I guess I've just never felt the need to have to rush things along with a dehydrator.

I've never been in that much of a hurry and mother nature does just fine by me.

Who knows, maybe some day I will change my mind.

 

 

Steve

Oh yeah! Just before I saw your post, I just put some primer (light coat) on the '68 'Vette I'm restoring. Now, I'll let this sit for a day despite the light coat, then I'll go back and put on the BIN Zinsser sealer on top of that. Another primer coat will follow, then color coats. So yeah, we're talking probably a several day process which doesn't bother me as that's how 1:1's are done. In this case I'm in no hurry as I've got plenty of other things to do (1/8 scale '67 Shelby for instance) while the paint is drying.

I like to treat my paint jobs on bodies just as if they're real cars..............they're just 25 times smaller!  

[StevenGuthmiller]

1 hour ago, MrObsessive said:

Oh yeah! Just before I saw your post, I just put some primer (light coat) on the '68 'Vette I'm restoring. Now, I'll let this sit for a day despite the light coat, then I'll go back and put on the BIN Zinsser sealer on top of that. Another primer coat will follow, then color coats. So yeah, we're talking probably a several day process which doesn't bother me as that's how 1:1's are done. In this case I'm in no hurry as I've got plenty of other things to do (1/8 scale '67 Shelby for instance) while the paint is drying.

I like to treat my paint jobs on bodies just as if they're real cars..............they're just 25 times smaller!  

I agree Bill.

My paint jobs consist of Multiple coats of primer, paint and clear coat, (as many as 15 coats in all) and while I suppose it would speed up the process to dry each coat in a dehydrator, I always have plenty of other things to do during the course of a build.

While a coat of primer or color dries for a couple of hours, or over night, I can be working on chassis, engine or interior assemblies.

There's never a shortage of things to work on, and I'm never in a hurry.

Besides that, my shop is too small already.

Another piece of equipment to trip over is not appealing to me at this point.

 

 

Steve

[ZTony8]

Enamels dry by oxygen intake so if you can increase that then an enamel should dry faster. Or am I wrong in my thinking on this?

[peteski]

I never heard that "standard" enamels need UV light to cure.  Yes the have 2 stages for drying.

1. solvent evaporating leaves the enamel dry but soft.

2.after the solvent evaporates the resin in the paint's binder starts to cure (its chemical properties change). I have heard that oxugen is needed for this process to progress (like Tony states).  The curing process can take long time, but heat will accelerate it (heat accelerates lots of reactions).

But if there are UV-curable enamels then sure, UV light will be needed for the final cure.  However I doubt that any of the hobby enamels are specifically UV-curable.  But if some specific information is available to prove otherwise, I'm all eyes.

[Tommy124]

8 hours ago, peteski said:

I never heard that "standard" enamels need UV light to cure.  Yes the have 2 stages for drying.

1. solvent evaporating leaves the enamel dry but soft.

2.after the solvent evaporates the resin in the paint's binder starts to cure (its chemical properties change). I have heard that oxugen is needed for this process to progress (like Tony states).  The curing process can take long time, but heat will accelerate it (heat accelerates lots of reactions).

But if there are UV-curable enamels then sure, UV light will be needed for the final cure.  However I doubt that any of the hobby enamels are specifically UV-curable.  But if some specific information is available to prove otherwise, I'm all eyes.

I second your opinion. AFAIK "UV-colors" (in the sense of colors requiring UV-light for curing) contain special UV-activators which I doubt are part of modelling paints. That kind of UV-stuff is, for instance, used in paper printing production in order to make sure for the ink to dry instantly without "splashing" - which allows to go for a higher production speed.

As to my own experiences... I have used Testors enamels for the first time since the 90's on my current project and was a bit shocked that the curing process actually took around 72 hours. Although the Testors website told me that this is within the usual range for their enamels. As I needed to go for some additionals paint layers and will consider to further use Testors enamels on other projects, I decided to get me a "reasonably priced" food hydrator with a timer. The first test went very well. I left the painted body in the hydrator for around 6 hours at 110 °F and it was touch-dry to such a degree that it could be handled for further working on. So I'm really glad I went for it . 

Edited May 6, 2019 by Tommy124

[randyc]

I have a "new" dehydrator.  Very simple.   Not even on/off switch.  I asked for it for Christmas with no other criteria when my first one finally died.  With that said, this one seems hotter but I have not put a thermometer to it to check.   But I am very cautious about leaving things in it without checking them often.  Or just putting a body shell on top over the vents wheree the hot air comes through but isn't quite so hot as inside.

the car in photo was painted with duplicolor black on Friday evening.   Dehydrated for an hour or so.  Left over night.   Body felt dry Saturday morning and I put on Testors Boyds Clear thinned with lacquer thinner.   Then in the dehydrator for a couple hours.    Unplugged dehydrator.   Came back Sunday morning and heated for a couple more hours.   Still has a slight smell to it.  Yes I do use the sniff test.   It's pretty dry now but I still would not handle the body for more than sliding the chassis up under it in this photo.   Still needs more time to dry before polishing the dusties out.  I think heat/cool cycles help as well.  the heat can cause the paint to be softer, but a cooling cycle seems to help it harden.  And that's just my opinion since I only use dehydrator when I'm with it.  My building area is in my outbuilding so I am hesitant to leave it on when I'm not there.   And no my VCR doesn't flash 12:00.  LOL  I would leave things in my old dehydrator for 24 hours, but not this one.  It just seems too hot.

Without the dehydrator, this wouldn't be anywhere near ready to touch.  

I don't think there is anywhere near a constant timing for paints.   Guidelines maybe.   I think this week I should check temp in the dehydrator.   It's been in storage til recently with a divorce etc.  But I finally had a place for it and have been using it a lot over the last month.  

And do be careful with what you put in any dehydrator.  My last one seemed cooler but warped a couple of Lindberg bodies very badly.  

[Gramps46]

Thanks for sharing the info Randy.

[MrObsessive]

Randy, your tip about checking bodies often is a VERY good one, especially for those of us that like to do opening panels such as doors and whatnot. Years, ago when I was building my '63 Ferrari 250 GTO, I put the body in the dehydrator to speed things up a bit. I had opened the doors on it and thank goodness I checked the body when I did!

I could see where there was a slight warp beginning to start on the body right at the door jambs (the weakest part) and fortunately, I was able to straighten things back out. This was despite having the thermostat set at 105º which is about ideal for drying.

Certain plastics may warp sooner than others so yeah.......you want to keep an eye on any bodies you put in there, especially if anything is opened up.

[peteski]

12 hours ago, randyc said:

I have a "new" dehydrator.  Very simple.   Not even on/off switch.  I asked for it for Christmas with no other criteria when my first one finally died.  With that said, this one seems hotter but I have not put a thermometer to it to check.   But I am very cautious about leaving things in it without checking them often.  Or just putting a body shell on top over the vents wheree the hot air comes through but isn't quite so hot as inside.

And do be careful with what you put in any dehydrator.  My last one seemed cooler but warped a couple of Lindberg bodies very badly

 

I also have very inexpensive basic dehydrator (shown here).

It has a 40W element on the bottom and no temperature control. There are adjustable shutters on the bottom and in the lid.  I have the shutters adjusted to give me a temperature range 100-110 deg. F.  I have an inexpensive meat thermometer stuck through one of the holes in the lid to indicate the temperature inside.  In the 30 or so years I have been using it, I have never damaged or warped any items I dry in it.

[Dave Van]

I use Dupli-color and Tamiya spray cans. I can prime, paint a two color paint job in about 3 hours total. If I start in the morning I can easily be decaling that evening. It has made a huge difference in my enjoyment of the hobby. I have used mine for almost 30 years now. 

[randyc]

10 hours ago, peteski said:

I also have very inexpensive basic dehydrator (shown here).

It has a 40W element on the bottom and no temperature control. There are adjustable shutters on the bottom and in the lid.  I have the shutters adjusted to give me a temperature range 100-110 deg. F.  I have an inexpensive meat thermometer stuck through one of the holes in the lid to indicate the temperature inside.  In the 30 or so years I have been using it, I have never damaged or warped any items I dry in it.

I looked yesterday - temp and time contorl units for around $36 delivered via Amazon.   Maybe soon... good point on the thermometer.

[randyc]

9 hours ago, Dave Van said:

I use Dupli-color and Tamiya spray cans. I can prime, paint a two color paint job in about 3 hours total. If I start in the morning I can easily be decaling that evening. It has made a huge difference in my enjoyment of the hobby. I have used mine for almost 30 years now. 

I did a NASCAR car like that once.   Krylon and duplicolor paints.  Plus the enamel small brush paint details.  And the dehydrator.  Built the whole car in an afternoon and turned out pretty nice, especially considering it only took an afternoon.

[NOBLNG]

They had them on sale at Canuck Tire so I bought a second one. The space inside is rather small so a second one is nice. I only spray in the garage and sometimes it would be nice to have one in there and one in the house. I'll admit I am a very impatient person, so the dehydrator is a must for me!

[Tommy124]

23 hours ago, MrObsessive said:

Certain plastics may warp sooner than others so yeah.......you want to keep an eye on any bodies you put in there, especially if anything is opened up.

You surely have a point there, Bill. The first kit I dried some days ago (the only one so far) is an old Monogram one from 1984, the thick stuff I like to call "panzer plastic"...  Surely needn't worry about anything warping in that, but with modern kits, Tamiya, Hasegawa etc. - they certainly have softer plastic. And I agree on keeping an eye on the process every once in a while, better to be safe than sorry...