School me on Retarder.....Pro's & Con's

'68 Coronet R/T said:
This picture is the very first time I tried retarder in the final coat of clear. I normally use Slow Activator and Slow reducer but thought I would give the retarder a try since temps were in the mid 90s. The result was better than I expected. No cut or buff on this panel.

Must admit, I never thought about using it in a base coat. Though I could see that painting a bus or an RV it could prove helpful.
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Wonderful, just wonderful. Glass reflection at its best!

This is why I'm inquiring about the usefulness of retarder. I understand now it can be used for clear coat, 2k primer, and epoxy.

It's very useful in hot weather, and can be used in a metallic base coat if you know what your doing, and for large panel spraying.

My question to you is, how did you mix it in your clear? As an example, 4:1:1:10% retarder?
 
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Chris, yes wet edge like on a roof or large hood. I also like the idea of letting overspray melt into the paint. It sounds like retarder will do that.

Someone had mentioned that retarder can cause loss of gloss in clear coat, why is that?
 
MP&C said:
The other area where it may help, a hard to spray metallic on a large panel (think wagon roof) may dry/flash before the metallic particles get a chance to settle in where they belong. This may appear as a mottling or tiger striping. The retarder will give the metallic particles more time to properly settle..
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To add some context to my rambling here…. When we had the wagon painted (I didn’t do it) the body was mounted on a rotisserie to help out in getting to all the out of the way places. The roof was the first item done, and the car was rolled up on the side so you could spray straight into the roof. Naturally, it would be rotated flat between coats so that the metallic particles could orient themselves. Only with as large an area as what was there, the base was about dry by the time the car was rolled back flat, and yes, it left mottling/tiger stripes. This was done two more times using varying degrees of slower reducer with little effect (yes, summertime). Paint re-blocked, the final coats were done using retarder, which gave sufficient time for the metallic particles to get oriented after rotating the car back flat. He also said that it was a couple hours or so between coats but there was no more issue with tiger stripes. So I would 100% agree with Chris, this should be a last resort. But if nothing else works for you, consider it an option.
 
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MJM said:
Wonderful, just wonderful. Glass reflection at its best!

This is why I'm inquiring about the usefulness of retarder. I understand now it can be used for clear coat, 2k primer, and epoxy.

It's very useful in hot weather, and can be used in a metallic base coat if you know what your doing, and for large panel spraying.

My question to you is, how did you mix it in your clear? As an example, 4:1:1:10% retarder?
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This was back in 2015 so I don't have the SPI Tech Manual for that year still.

Here's what it said in 2017 and I used the 10% mentioned and highlighted below under Custom Work. (Three coats of clear and then adding 10% reducer to the last coat.)

Primers:
In the summer when 2K primers tend to dry too fast, add 2-4 oz per mixed quart of primer. This will also work very well when spraying an all-over in the 80 to 100 degree range and stop potential pin holing and dry edges.

Clears or Single Stage Paints:
For hot weather and all-overs in 80-100 degree heat, add 2-4 oz per mixed quart to slow the flash down or to prevent dry spraying.

We all have had the problem of spraying your last coat of clear, usually on a hood or deck lid, and out of nowhere comes solvent pop. Without waiting, pour the clear back into the mixing pail and add 10-50% of retarder. Again without waiting spray one wet coat or two If needed to wipe out the problem. This one step will save an extra day’s work to fix the problem panel.

Custom work where 3 or more coats are used, adding 10% this product to the last coat of clear will make an excellent flow coat.
Some shops use as much as 50% retarder but be careful until you know the product because it will flow!
We have feedback that some custom shops use 5-10% in every coat of clear for allovers as this is truly a product you can experiment with and it will save a lot of money down the road.

We do not recommend using this product when cooler than 70 degrees.
 
A little update on my flowcoated interior panels. First let me say, if you follow the advice / suggestions from the Pro's and Backyard hacks, you'll get Pro like results.

Sometimes it takes a few attempts to achieve that flawless finish but, it will come, just apply yourself. Also, there are no stupid/ dumb questions. If you're not sure, ask. Putting your pride in your back pocket will pay dividens towards the perfect paint job.

With that said, I like sharing my results for those who have, and for those who will, continue to guide me in my quest for the perfect paint job. Their guidance is what produced my results. This is a fact, and they deserve to be shown what has been achieved thru their words.



Panels flow coated 4:1:1 10% retarder
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Truck reflection
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House reflection
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Backside of panel. I was curious to see what epoxy looked like clear coated. Now I know.......
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i use it in basecoat all the time BUT for a very special use case where i am brushing and doing some artwork. one thing to note is that you need to use regular reducer in the base as well. the retarder is very slow but also very weak. the solvents in it are not strong enough to really dissolve or break up the basecoat. it can cause a little clumping of the base after some time if used by itself.
 
Jim C said:
i use it in basecoat all the time BUT for a very special use case where i am brushing and doing some artwork. one thing to note is that you need to use regular reducer in the base as well. the retarder is very slow but also very weak. the solvents in it are not strong enough to really dissolve or break up the basecoat. it can cause a little clumping of the base after some time if used by itself.
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So I completely understand when you say "regular" reducer. Does that cover fast, medium, slow, and extra slow reducer?

As an example, the BASF Diamont base I sprayed for my interior panels had a mix ratio of 1:1. I used SPI 885-4 slow reducer.

If, which I'm not, where to add retarder with slow reducer in my base, is this acceptable?.....or should I be using medium reducer that I'm assuming is "regular" reducer.

Thanks,
 
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Ahh i see your confusion. I should have worded that better. When i say regular reducer i dont mean medium. I am referring to fast to ex slow. reduce first then add retarder as necessary. With that said, for normal spraying i have never needed anything other than the normal range of reducers. Tweaking base like that i think is totally unnecessary.
 
Jim C said:
Ahh i see your confusion. I should have worded that better. When i say regular reducer i dont mean medium. I am referring to fast to ex slow. reduce first then add retarder as necessary. With that said, for normal spraying i have never needed anything other than the normal range of reducers. Tweaking base like that i think is totally unnecessary.
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Thank you for the confirmation. Your original wording to the seasoned painters made perfect sense, I'm sure. Now I understand.

Even though I don't like to say never, I don't see anything in the near future that would temp me to try retarder in base coat. I do however understand MP&C explanation of why it was used in the metallic base coat. Pretty voodoo trick means and method, used by an obviously seasoned Pro.
 
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Jim C said:
Tweaking base like that i think is totally unnecessary.
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Agree 100%. Only situations are examples like you mentioned, or spraying giant things like buses in high temps. My Dad used to refer me to the K.I.S.S. principle alot. It holds true for many things.
 
I've read that some guys use as much as 50% retarder.

With that said, I'm wondering if using that much retarder lowers the solids content of the clear?

Or does the reducer just disappear after its done it's job to extend open times and help flow out material?
 
Per ounce reducer, or retarder, adds sprayability to solids for basically no other reason. If sprayed say a 4:1:1 ratio, then reduce a 4:1:2 ratio, would require more coats to equal the final solids
 
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texasking said:
Per ounce reducer, or retarder, adds sprayability to solids for basically no other reason. If sprayed say a 4:1:1 ratio, then reduce a 4:1:2 ratio, would require more coats to equal the final solids
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Awesome...... I'm smarter after reading that information. I would not have consider it would take more sprayed coats.

I think for my own edification, this winter I'm going to do a test piece and reduce clear with retarder 10%, 20%, 30%, 40%, and 50%. This should let me know the spraying characteristics of each % of retarder used, and it may show me just how much material I can stack before obvious waves in the clear show up.

I really had no idea of the science behind automotive painting when I started my Barracuda. It has really opened my eyes of why it can take years and years to learn the in's and out's of painting. I doubt I'll ever get there due to age but, I'm feeling confident I'll beable to paint my own vehicles.

All made possible because of fellas like yourself explaining technics, processes, materials and tooling to accomplish the task at hand.
 
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