Eastwood Fast Etch Inconsistency

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PostPosted: Sun Jan 02, 2022 9:40 pm
I've learned time and time again that I should always consult the forums before making rather uneducated guesses. Nonetheless, I tend to spend far more time fixing stupid mistakes than browsing forums.

This habit has put me in a frustrating predicament. I spent a long time sandblasting under my car in preparation for some epoxy and subsequently undercoating. The clean metal sat for two days because of unexpected delays to the epoxy *facepalm*. The surface looked almost entirely clean of surface rust after this period, yet I still convinced myself that there was light surface rust that had formed. Realistically, I probably would have been fine putting epoxy over LIGHT surface rust (am I correct in thinking this?). Unfortunately, I decided to use Eastwood's Fast Etch (phosphoric acid + zinc coating product) on some of the sandblasted surface to make sure there was zero rust.

This stuff is a pain. I originally used it according to Eastwood: apply and maintain wetness for at least 30 minutes and then wipe clean with either Acetone or one of their prep products. Then, I ran out of acetone and much of the surface was mostly dry. It was at this point that I went to the forums and realized I was wasting time and needed to clean up this Fast Etch headache. I switched to using dawn+water rinsing to neutralize the wet acid as others suggested. My process was as follows:
1. rewet Fast Etch (with Fast Etch)
2. Spray with lots of dawn+water from spray bottle
3. Wipe with tap water
4. Dry with shopvac blower

Then, REAL flash rust formed and the surface looked way worse than just clean sandblasted. I played around with my timing and redid the process without rust forming, but the surface still looks unpaintable. What are all of your thoughts on my situation? do you think it's find to put epoxy over if there are lighter spots on the metal? The white spots look kind of like the hard water stains on faucets. Any and all input is greatly appreciated.

Many thanks,
Tyler
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Picture is upside down for some reason. Ignore the bracket at the end of the trans tunnel. I haven't messed with that yet. Flash rust eliminated, completely dry. (current state)



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PostPosted: Sun Jan 02, 2022 11:35 pm
:welcome: i think most epoxy's have a rust inhibitor but check the brand that your useing to be sure. being its inside the car another way to go if your deeply worried about the flash rust is to use an etch primer then go to your undercoating. seriously light flash rust on the inside, epoxy it an undercoat it. it will last forever. you can also rub the flash rust off with a scratch pad.
Jay D.
they say my name is Jay



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PostPosted: Mon Jan 03, 2022 12:22 am
badsix wrote:it will last forever.
Jay D.


What a gorgeous phrase.

The flash rust isn't super concerning anymore with what you and others are saying about epoxy's herculean abilities. I just hope it will stick to the surface.

Just for clarity's sake, this is actually outside the car under the rear seats. The picture is just accidentally upside down.



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PostPosted: Mon Jan 03, 2022 12:09 pm
I use a Cold galvanizing system which sounds similar to your Eastwood product BUT It must used and neutralized properly! In My case due to the size of the project requires large amount of product and More than one person doing the work in my case I have a least 3 people all on board on how to do the work.

This entails applying the 1st product scrubbing it in with scotchbrite pads Then while keeping the surface wet with the product for amount of time specified by product then rinsing thoroughly with water as it dries it does flash rust!

Then Part 2 Product is applied and again keeping surface wet with product and scrubbing with Scotchbrite pads working it in for the specified amount of time specified by the product instructions keeping it wet with the product all the time never allow to dry on panel.
Then rinse thoroughly with water then washing with soap and water rinsing thoroughly and allowed to dry and it never flash rusts again!

If your gonna play with these types of products you must follow instructions to the letter.
IF you don't get the product off correctly it can remain on your metal and adversely effect your paint EPOXY in particular! causing adhesion problems.

IF in doubt switch gears and Go with an Etch Primer instead.
Finding out you have a Adhesion problem after fully painting your car is NO FUN and a waste of money.

the Products I use are made by Dupont now Axalta and by PPG when used correctly there is no better treatment for protecting your metal or removing light surface rust.
Dennis B.
A&P Mechanic, FCC General radio Telephone Operator
Line Maintenance A&P Mechanic and MOC Tech specialist.

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PostPosted: Mon Jan 03, 2022 12:55 pm
I would take some 80 paper and scuff the surface with it.
Clean with automotive Wax and Grease remover by spraying it on and wiping it off before it dries with a clean shop or microfiber towel. Let this dry and blow the area off with compressed air.

Shoot two coats of black epoxy primer, waiting the proper flash time between coats, and call it good. Undercoat can be applied if desired, directly over the epoxy. Check the topcoat window on your epoxy and if you stay within that window, you don't have to sand it before applying undercoat.
1968 Coronet R/T


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