17 replies to this topic

[JonnyAlpha]

Hi, I need a bit of advice on applying Filler, I looked through the painting guide but it doesn't go into primer in detail. I remember seeing a really good guide somewhere but for the life of me cannot find it, maybe I saw it on the Mig Welding Forum?

Anyway should I fill before or after priming or Acid Etching bare metal or doesn't it matter. And for dings in paintwork can you fill over paint after keying it?

Edited by JonnyAlpha, 13 July 2013 - 03:00 PM.

[JonnyAlpha]

Sorry just found it.

http://www.mig-weldi...body-filler.htm

[jaydee]

If you're using etch or zinc primer you need to prime the bare metal or it wont work, then filler over etch (or zinc, whatever you decided to use) primer . Then obviousely paint primer.

[myredmini]

Filler will adhere to bare metal just abrade well with a course grit e.g p40 or p80.

Dan

[HarrysMini]

I always use filler on bare metal. I have always found it doesn't adhere to primer properly and in some cases has just peeled off on top of the primer. Car body filler is designed to be used on abraded bare metal. Then prime (I don't etch prime over filler but I know plenty of people who do).

[myredmini]

Etch primer burns itsself or eats into the metal so to speak offering protection and helps the primer adhere very well to prevent chips and flaky paint. Its only useful on bare metal.

[jaydee]

Same applyes to zinc, it needs electrical conduction, you must filler over primer or it wont work

[midridge2]

Same applyes to zinc, it needs electrical conduction, you must filler over primer or it wont work

 

filler should allways be applied onto bare metal, yes etch is for bare metal to help the primer stick but the chemicals can bleed through filler if it has not fully dried if you put filler over etch.
 

[JonnyAlpha]

Sorry guys I'm being a bit thick here.
I thought I should apply an Etch Primer on my bare metal but I also need to fill but Etch Primer doesn't like going on filler and filler should be applied to bare metal. So what do I do?

[midridge2]

Bare metal then put your filler on and rub down, then etch around it if you have bare metal around the filler then when dry high build primer over the filler and etch primer. 

[JonnyAlpha]

In the last stage when the filler is dry do you mean that as a last stage spray high build primer over both the filler and the etch primer. I guess this is to blend in any differences between the two.

[midridge2]

With any filler repair you will take all the paint off in a bigger area than you are filling, when you have rubbed down the filler mask over the repair and blow a mist coat of etch over the bare metal, when fully dry remove the masking and spray the area with high build primer.

[JonnyAlpha]

In the last stage when the filler is dry do you mean that as a last stage spray high build primer over both the filler and the etch primer. I guess this is to blend in any differences between the two.

[JonnyAlpha]

Sorry midridge2 i have been in the car all day and in and out of mobile data signal so I wrote my response above before your replied but it did not get sent until after. I fully understand the process now thanks.

 

The planned steps are:

 

1. Dress all welds with a grinding disc and finish off with flap discs.

2. Sand down entire area with 80 / 100 sandpaper as required to remove any surface rust, brush / hoover away dust.

3. Clean up with panel wipes to remove any grease.

4. Key any areas to be filled that were not touched by the Flap Discs with P40 or P80 grit paper.

5. Apply filler to required areas.

6. Sand down filler as required, brush / hoover away dust.

7. Mask over filled area.

8. Clean up bare metal with sandpaper to remove any surface rust that has appeared since step 2, hoover / dust.

9. Panel wipe again to remove any additional grease.

10. Mist / Dust coat of Etch Primer over any bare metal, I guess no keying is required with Etch Primer?

11. Lightly sand entire area with low abrasive grit 100 / 120, dust / hoover and spray with high build primer.

 

Store Mini in dry environment and await painting.

 

Additional Info:

Some good info here which goes into more detail: http://www.mig-weldi...body-filler.htm

This also suggests using knifing putty and stopper before applying high build primer before step 11. 

 

I have also been advised for filler to use U-POL Fantastic

 

Please feel free to correct my plan?

 

[myredmini]

I wouldn't mask the filler off. Just blow the etch around it. It won't cause any harm if over spray hits it.