Retarder and Rub-Out
Adding retarder to a pre-cat finish won't prevent you from rubbing the finish out, but it may affect your wait time. April 30, 2006
Question
I read somewhere in the Knowledge Base that if you added retarder to pre-cat it would never dry and would be impossible to rub out. This was just one person’s opinion and my buddy (an experienced finisher) said he had never had a problem with it. Does anyone have any knowledge to support or contradict this statement?
Forum Responses
(Finishing Forum)
From contributor A:
That’s just not true. I use precat everyday of the week, including today! I won’t even spray it without retarder. PreCat isn’t so good to rubout in the first place, but certainly retarder doesn’t make it any worse for the rub.
From contributor B:
That would be true only if you added too much retarder into the pre-cat. Ask your supplier for the right retarder, and the proper amount to add.
From the original questioner:
I have added about 1.5 ounces per gallon. That is what I normally use.
From contributor B:
Don't be a chemist, ask your supplier or manufacturer, unless it’s printed on the label or in their catalogue.
From the original questioner:
This is in the range of what they recommend. I have been using this amount safely, without problems for the last 5 years. However, this question relates specifically to rubbing out. Will retarder keep the finish from reaching a level of hardness required for a successful polishing? I am in no real rush so I can wait several days to a week for a proper cure. Thanks for the advice, hope I can get more from people who have done this either successfully, or ran into trouble due to the retarder
From contributor B:
It will not affect the rubbing out of the coating. The longer you can wait, the harder the coating will be to rub out. If you can wait 72 hours that would be normal, if not, 48 is OK.
From contributor C:
Ask also about adding catalyst to the Optiset. I think you can put 5% in to ensure the hardness.
From contributor D:
Use 3% by Volume catalyst for Optiset.
From Paul Snyder, technical advisor Finishing Forum:
Retarder just slows the cure time Ryan. The less retarder you use, the less the cure time will be extended. The more fully the finish is cured, the less it will shrink after you rub it out.
From contributor B:
Retarder, also increases the "flow out". I don't know which chemicals are in the retarder, but it seems like a small amount for a gallon. If the 1.5 is working for you, and it must be, then stay with it. When in doubt, make up your own samples.
From contributor E:
I have Sherwin-Williams put retarder in my pre-cat as part of my standard formula. That's what I love about SW. You can have them mix anything the way you want it.
From contributor C:
Well now, there's something I didn't know. I thought retarder just extended the flash time, which would allow better flow out, or leveling. I didn't know it increased the cure time as well.
