Two-pack paint over etch primer: OK?
Discussion
I'm painting a refurbed master cylinder and brake booster before installation. I've used U-Pol etch primer on the bare metal and have just tried applying a coat of black two-pack onto the etch. The results are not good. It looks like the two-pack is reacting with the primer in small spots.
Is this a bad combination? I've sprayed straight onto etch primer before without problems but never with two-pack.
I'd be grateful to learn from others' advice or experience.
Is this a bad combination? I've sprayed straight onto etch primer before without problems but never with two-pack.
I'd be grateful to learn from others' advice or experience.
With the lack of responses I just blundered on regardless 
and it's turned out OK after all. With thinners I cleaned down the areas that appeared to be reacting and then sprayed them again and it's all looking OK again now.
I'm sure I'll do a better job next time but so far it's OK. The two-pack fumes will probably kill me before any rust starts to show.
and it's turned out OK after all. With thinners I cleaned down the areas that appeared to be reacting and then sprayed them again and it's all looking OK again now.I'm sure I'll do a better job next time but so far it's OK. The two-pack fumes will probably kill me before any rust starts to show.
It is all about the prep work. Most parts need at least 2 good scrubs/washes in a degreaser. Then air dry. Always use gloves when handleing the parts. Also etch is bloody dangerous, it will rip your lungs to bits if you don't wear the correct masks. Loads more dangerous than 2 pack, that will kill you over a longer period! Pm me if you need anymore advice.
Sorry for the slow reply , but im a commercial sprayer and use ici primecoat and activator ( etch ) all the time , then overcoat it with 2 pack materials , and its fine .
Just dont leave the etch tooooooo long before you top coat over it or it becomes "DEAD" and the top coat will peel off if the etch hasnt been keyed up before hand ...
ALL 2 PACK PAINTS need proper breathing kit, whether its etch or top coat .
Ever seen jelly set ?? well if you breath in the vapours of 2 pack paint this is how it will set in your lungs , slowly filling them up ....
Its lethal stuff and should be treated with respect .....
Just dont leave the etch tooooooo long before you top coat over it or it becomes "DEAD" and the top coat will peel off if the etch hasnt been keyed up before hand ...
ALL 2 PACK PAINTS need proper breathing kit, whether its etch or top coat .
Ever seen jelly set ?? well if you breath in the vapours of 2 pack paint this is how it will set in your lungs , slowly filling them up ....
Its lethal stuff and should be treated with respect .....
Edited by 106 gti on Sunday 7th October 15:34
Thanks for the latest replies. I appreciate your responses.
The outcome of this experiment wasn't too bad. The patch of twopack that reacted in fact was relatively small - perhaps 1cm x 2cm. It was just the first coat that didn't lay down as I'd expected, but after that it settled OK, apart from this one small patch. No amount of cleaning, rubbing down and repainting would remove this small area of reacting paint, so I guess maybe the metal has some porosity at that point and it's showing through.
However, I'm very disappointed with the ease with which two pack appears to dissolve when it meets other chemicals. My brake master cylinder has been painted for two weeks and I baked it gently in the oven for a couple of hours (at about 40 degrees) so I assumed the paint was properly cured. However, brake fluid dissolves it instantly (not surprising perhaps) and so does brake cleaner. I wasn't aware that brake cleaner was particularly damaging to paints - I've seen mechanics spray it indescriminately all over my Audi's engine and components with no ill effects. Am I unlucky that it's dissolving my nice new two pack?
I didn't use a mask to paint these two components - I just did lots of quick coats in my garage with open doors and held my breath as much as I could. Not scientific, but I'm not working with the stuff continuously.
The outcome of this experiment wasn't too bad. The patch of twopack that reacted in fact was relatively small - perhaps 1cm x 2cm. It was just the first coat that didn't lay down as I'd expected, but after that it settled OK, apart from this one small patch. No amount of cleaning, rubbing down and repainting would remove this small area of reacting paint, so I guess maybe the metal has some porosity at that point and it's showing through.
However, I'm very disappointed with the ease with which two pack appears to dissolve when it meets other chemicals. My brake master cylinder has been painted for two weeks and I baked it gently in the oven for a couple of hours (at about 40 degrees) so I assumed the paint was properly cured. However, brake fluid dissolves it instantly (not surprising perhaps) and so does brake cleaner. I wasn't aware that brake cleaner was particularly damaging to paints - I've seen mechanics spray it indescriminately all over my Audi's engine and components with no ill effects. Am I unlucky that it's dissolving my nice new two pack?
I didn't use a mask to paint these two components - I just did lots of quick coats in my garage with open doors and held my breath as much as I could.
Not scientific, but I'm not working with the stuff continuously.Came here to find an answer to the etch primer then 2pak conundrum (very useful thread from btw, thanks) and came away wondering if the OP survived some 18 years later??
In case you're wondering I'm looking to cure a flaking paint issue on the reverse side of some Audi LeMans Alloys on a 2009 A4. Interestingly, my ancient seeming A4 is not even as old as this post!
If you're reading this way in the future, I hope the world is a better place than it is now.
In case you're wondering I'm looking to cure a flaking paint issue on the reverse side of some Audi LeMans Alloys on a 2009 A4. Interestingly, my ancient seeming A4 is not even as old as this post!
If you're reading this way in the future, I hope the world is a better place than it is now.
Ha ha, what a great update!
I love the fact he baked it in his oven for a couple of hours, I bet his missus wasn't home!! Im not sure you will fit your alloys in your oven will you?
PS, you are better using Epoxy primer on bare metal than etch nowadays as long as its clean and free from rust.
I love the fact he baked it in his oven for a couple of hours, I bet his missus wasn't home!! Im not sure you will fit your alloys in your oven will you?
PS, you are better using Epoxy primer on bare metal than etch nowadays as long as its clean and free from rust.
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