Explain retarder to me.

CK-2

Active Member
So what’s the difference in using retarder vs just using a slower activator in Universal?
If it’s 80 degrees and I’m using slow activator what’s the difference in adding a little retarder to the slow vs just using extra slow activator?
Will retarder increase runs by slowing flash times?
 

Chris_Hamilton

Trying to be the best me, I can be
Retarder lengthens the open time and the flash time. It allows the clear to flow more before flashing. It doesn't significantly affect the cure time. Cure time is still dependent on the speed of activator you use and the temperature. THat being said the speed of the activator affects both the open/flash time and the cure time. The amount of effect of the retarder is also dependant on the temperature. Cooler=more effect. Hotter =less effect. Also more retarder used = greater effect, less retarder used = lesser effect.
Yes the possibility of runs increases with the amount of retarder you use.
 

Chris_Hamilton

Trying to be the best me, I can be
I would also add that one of the best uses for retarder is when you have to spray in hot to very hot conditions. Using retarder in hot to very hot conditions allows the clear to perform as it's intended and makes it much more usable in unfavorable conditions. It is also useful in very hot conditions in preventing solvent pop.
 

sprint_9

Rookie
Retarder works wonders in the heat like Chris said. If it's hot and all you have is slow activator you might run into trouble with dry spray. Put a little retarder in the mix and go from being frustrated with dry spray to something respectable. It really was worth its weight in gold for me last summer.

I should elaborate on my comments above. I mentioned using retarder with slow activator when it was hot. Hot is a loose term, I was a northern hot. My example was about 85-90, with high humidity on a large piece. Retarder with slow, slow was all I had, worked really good. If I remember right I was adding 2 ounces per ready to spray Qt. and an extra couple ounces on the last coat.
 
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jcclark

Oldtimer
Will retarder increase runs by slowing flash times?
Not if you substitute for less reducer.
For example: If your mix was going to have 6 oz. reducer,
use 5 oz reducer and 1 oz retarder. (Same 6 oz. reduction)
I like to over substitute which makes for less runs because the mix is less reduced.
I'll use 3 oz reducer and 2 oz retarder for a lesser total amount of 5 oz.
Most times I use way more than that to get it to really work and most
will say it's to much retarder but it works for me.
But I think the trick is using retarder only on the last coat to melt everything in
which lessens the run chances even more.
 

Chris_Hamilton

Trying to be the best me, I can be
Some of the ways I use it.
I have used it in Euro and Universal. Main use for it is in hot weather. Above 90 degrees , adding 2-4 oz per 32 oz of RTS (ready to spray) clear allow the clear to behave like you were spraying it @75-80 degrees. I usually will only use it in temps around 85 or above. Once temps hit 95 degrees using some throughout is almost mandatory to allow the clear to perform as intended.
I like to use a small amount throughout, meaning every coat. With Euro especially using some throughout really allows it to flow and stay open so that you don't have an issue with dry spray on an Overall.
I shown these pics before, but they illustrate the point well. This was done with Euro 4:1:1 (895 reducer, slowest activator) and approximately 3-4 ounces of retarder per 32 ounces of RTS clear. Three coats. retarder used throughout. Complete front end and front doors, basecoat blend into the doors. Temps in the booth that day were 106 degrees. It was brutal. With other clears you could not spray this without making a giant mess. Using the Euro and retarder it laid down perfectly. No texture, no solvent pop.
IMG_20160721_191008165.jpg


This one was done in similar conditions. Over 100 degrees in the booth, Euro 4:1:1 (895 slowest activator)3-4 ounces of retarder per 32 ounces of RTS clear. Complete front end and doors, basecoat blend into the doors. Three coats, retarder throughout. No buffing. Retarder really is "the painters best friend" as Barry says.
IMG_20160726_134315138.jpg


Same principles will apply to Universal Clear as well.
 

CK-2

Active Member
So let’s say I have extra slow activator and I’m spraying universal on an 80 degree day. I really wouldn’t need the retarder? But if it was 85 or above like you mentioned retarder would help?
Or if I only had slow or normal activator on a hot day that really calls for a slower activator I could add some retarder to the mix to slow down the flash ? Enabling me to keep it wet long enough to not be spraying into a dry edge or dry spray settling on my clear before I can finish?
 

Chris_Hamilton

Trying to be the best me, I can be
So let’s say I have extra slow activator and I’m spraying universal on an 80 degree day. I really wouldn’t need the retarder? But if it was 85 or above like you mentioned retarder would help?
Or if I only had slow or normal activator on a hot day that really calls for a slower activator I could add some retarder to the mix to slow down the flash ? Enabling me to keep it wet long enough to not be spraying into a dry edge or dry spray settling on my clear before I can finish?
Main use is for hot weather. Secondary use is for getting the clear to flow more. Flow coating, is one example but something I wouldn't recomend someone try unless they have a lot of experience spraying. 80 degree day no real need especially if you are using slow or very slow activator. I would never use anything but slow or very slow at 80 degrees or over irregardless if I used some retarder with it. The fast activator shouldn't be used above 75 and even then only with small jobs. Motorcycle tank, fender, etc.
The retarder shouldn't be used as a substitute for the correct activator for the temperature you are spraying in.

Summary: Universal Activators and Retarder
Fast activator= Sub 75 degrees single or two panels maximum 65 or so (coldest I will shoot clear at) it would work well for multi panels. Personally I will not shoot an overall with fast even at 65-70 degrees. I would go with slow instead. (I would not use retarder with fast activator.)
Slow activator 75-85 degrees multi panels, can be used for overall especially if closer to 75 than 85. Retarder can be added in smaller amounts to help with open and flash times and to allow for the clear to flow as intended or slightly more.
Very Slow 80-95+ degrees and higher, Lower temps will flow more (be careful) above 85 should be considered mandatory if doing an overall. Retarder can be added in larger amounts to help with open and flash times and allow for the clear to flow as intended.

Retarder is not intended to be a substitute for the proper activator for the temperature you are spraying at. If you try that you are own your own so to speak. Might be ok or it might not work very well.

That's about all I can tell you about retarder.:)
 
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rdransman

Member
<snip>
Retarder is not intended to be a substitute for the proper activator for the temperature you are spraying at. If you try that you are own your own so to speak. Might be ok or it might not work very well.
<snip>
I agree. It always was my understanding that, at the molecular level, a given number of molecules of the activator (1, 2 etc.) joined with one or more molecules of the clear. I do not mess with the 1:1 ratio required for Universal Clear, for instance. If I feel the need to add retarder due to high temperature I do that, but I don't change the specified ratio of the basic product.
 
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sprint_9

Rookie
It always was my understanding that, at the molecular level, a given number of molecules of the activator (1, 2 etc.) joined with one or more molecules of the clear. I do not mess with the 1:1 ratio required for Universal Clear, for instance. If I feel the need to add retarder due to high temperature I do that, but I don't change the specified ratio of the basic product.
I believe he means dont take clear mixed with medium activator, add a bunch of retarder and go to town in 90 degree conditions.

I think you can maybe bump into the bottom of the next step of activator. Say its 90, you should really probably have extra slow, but retarder and slow can get you by.

I edited my post above after reading Chris's info. Mine was confusing with the word hot, hot is a wide range depending where your at.
 

Chris_Hamilton

Trying to be the best me, I can be
It always was my understanding that, at the molecular level, a given number of molecules of the activator (1, 2 etc.) joined with one or more molecules of the clear. I do not mess with the 1:1 ratio required for Universal Clear, for instance. If I feel the need to add retarder due to high temperature I do that, but I don't change the specified ratio of the basic product.
Put another way. Use the correct activator for temps you are spraying in. Don't use retarder to try and make a faster activator work in place of the correct activator for the temperature and what you are spraying.
 

texasking

Active Member
hot is a wide range depending where your at.
Today it was cool, 91 and heat index under 100. I don't even bother ordering anything but 895 and slow(Euro) or extra slow(universal) hardener from June- mid September, and keep a full can of retarder as a backup ready to go. I've been experimenting replacing portions of the reducer in Euro, mixed 4:1:1, with retarder. Have gone as far as 1/2 895, 1/2 retarder with great results, but heat index was 110-115 that day.
 

Barry

Paint Fanatic
Staff member
A bunch of perfect answers!
With retarder it is what works best for you no
matter what percentage you use.

Play bench chemist with it, and it can make you turn out work that requires less buffing.
 

Chris_Hamilton

Trying to be the best me, I can be
What temperature is 4001-4 Normal Activator (multi panel) for use in Universal Clear designed to be used at when doing an over all?
The multi panel activator is pretty fast so it's not really going to be suited for an overall IMO. Small car you could probably get away with it in 70 degree temps anything warmer and/or bigger vehicle I would say it's not really suitable. That being said you can blensd activators with the UV Clear so you may be able to blend a slow or very slow so that you can use some of your multi panel. If you are painting in pieces it would be much more suitable. I don't claim to be an expert as I don't ever use fast or multi panel. Only the slow and very slow. Barry would be the one to ask.
Text Barry on the Tech Line for an exact answer.
404.307.9740
 
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