Sanding etch primer

[ouchmyfinger]

Am i right in saying that not all primers can be wet sanded, if that is the case why! and do makers state so on the tin.

a child of 5 would understand this. Send someone for a child of 5.....
GROUCHO MARX

 

[steveo3002]

never really come across any automotive primers that cant be wet sanded

etch is usuayl more of a coating to make the high build primers stick to bare metal , so not really the sort of stuff you sand , and most primers suck up water and may cause issues later on , so dry sanding can be a better option

 

[norsa]

If i remember correctly, you dont want to be wet sanding polyester primers for no apparent reason. I used to use U-pol reface which was a 2k polyester primer/filler and it was not reccomended to wet flat it. Nowadays, 2k high builds are far superior so its not necessary to use it. It was a while ago so i stand to be corrected.
Nick

 

[Daz2012]

Etch primer shouldn't be sanded at all,usually 1 dryish coat is all that is necessary,let it flash off,say 30 minutes and then on with your 2k primer .... and reface should be done dry.

 

[ouchmyfinger]

Etch primer shouldn't be sanded at all,usually 1 dryish coat is all that is necessary,let it flash off,say 30 minutes and then on with your 2k primer .... and reface should be done dry.

cheers guys that makes sense now, i know someone who wet sanded his etch, finished the panel with 2k, and about 6 months later the gloss coats started peeling........... i wonder if this is because etch primer contains acid and wet sanding it made it react ! (thoughts please)

 

[langy]

If i remember correctly, you dont want to be wet sanding polyester primers for no apparent reason. I used to use U-pol reface which was a 2k polyester primer/filler and it was not reccomended to wet flat it. Nowadays, 2k high builds are far superior so its not necessary to use it. It was a while ago so i stand to be corrected.
Nick

Reface is the same as spray filler Nick, you should never wet sand it as it sucks up water like a sponge !!!

 

[norsa]

Makes sense. It was nasty stuff as i recall, hard to flat anyway and had a tendency to crack. God bless Max 2k high build.

 

[langy]

Makes sense. It was nasty stuff as i recall, hard to flat anyway and had a tendency to crack. God bless Max 2k high build.

I wouldn't wet flat any primer Nick apart from epoxy, they all take in moisture in varying amounts, I've never had microblistering and I'm sure it's the wet sanding that causes it.