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 Post subject: Etch Primer
PostPosted: Sat Mar 12, 2011 11:28 pm 
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Just a quick question.

If i'm using etch primer on bare metal, but not using any spray putty;
How long do i need to leave the etch to shrink back before i lay colour on?

Minimum time?
Optimal time?

(can't find anything that says i need to leave it at all if there's only etch down, but want to make sure i get it right)

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PostPosted: Sat Mar 12, 2011 11:50 pm 
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arrggg just put a motor in it and a coat of clear, then just get it to the muster. Paint it afer lol


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PostPosted: Sat Mar 12, 2011 11:52 pm 
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CARTER_GT wrote:
arrggg just put a motor in it and a coat of clear, then just get it to the muster. Paint it afer lol


Even if i clear coated it, id still have to rub the lot back to bare and then need this question answered again ;)

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PostPosted: Sun Mar 13, 2011 6:37 am 
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Phat Kat wrote:
5. With your Etch Primer mixed, apply 2 coats. You must allow at least 5 minutes between coats, this is called flash off time. It is important to allow it to flash off between coats. For acrylic to cure, the solvents must evaporate, if you put it on too thick or too quickly, the solvents get trapped in and create little bubbles that become Pin holes when you sand. The ideal temperature for painting acrylic is 25-28 degrees. If it is cooler you need to leave it longer to flash off. If its only 20 degrees, you will need to leave it for about 15-20 min between coats. If it is more than 35 degrees don't paint. It will flash off too quickly and you will get pin holes. Despite common belief, it won't burn unless the car body is about 75 degrees or over. People mistake the solvent pinholes for heat bubbles. They are totally different. Leave for at least 3-4 hours

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PostPosted: Sun Mar 13, 2011 7:03 am 
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Adam - Don't put your colour directly over etch.

After your etch has been on for an hour you need to put on primer or primer/filler. If it is the next day then lightly rub the etch with a red scouring pad. The primer when rubbed flat will give you the base for the colour.

Etch just seals the surface and is only a light coat - it won't provide any build material. Opinions vary but I put on an etch, 2 coats of primer/filler, sand with 320 dry, then 2 coats of primer/filler and then wet rub with 800 grit, then the colour.

It is worth taking the extra steps because what looks good on the colour is only as good as what is underneath.

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PostPosted: Sun Mar 13, 2011 8:10 am 
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Thanks GT, but isn't that timeline in regards to how to wait until you put your filler over the top?
adamstuart wrote:
If i'm using etch primer on bare metal, but not using any spray putty;
How long do i need to leave the etch to shrink back before i lay colour on?

Or am i mixing up terms here, when i said not using spray putty, i meant not using surfacer.

miniDave wrote:
Adam - Don't put your colour directly over etch.

After your etch has been on for an hour you need to put on primer or primer/filler. If it is the next day then lightly rub the etch with a red scouring pad. The primer when rubbed flat will give you the base for the colour.

Etch just seals the surface and is only a light coat - it won't provide any build material. Opinions vary but I put on an etch, 2 coats of primer/filler, sand with 320 dry, then 2 coats of primer/filler and then wet rub with 800 grit, then the colour.

It is worth taking the extra steps because what looks good on the colour is only as good as what is underneath.


Thanks Dave, so primer filler is a bit of a must?
Was hoping there was a quicker way around it, as the filler needs a few days to shrink back (and time is of the essence right now)

Guess i'll have to just make time. Cheers dave

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PostPosted: Sun Mar 13, 2011 9:37 am 
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adamstuart wrote:
Thanks GT, but isn't that timeline in regards to how to wait until you put your filler over the top?
adamstuart wrote:
If i'm using etch primer on bare metal, but not using any spray putty;
How long do i need to leave the etch to shrink back before i lay colour on?

Or am i mixing up terms here, when i said not using spray putty, i meant not using surfacer.



Not sure, I'm not a painter, but ask Phat Kat, he'll know, although one place I worked at did put down prime etch and then colour over that. Maybe it was a special prime etch, they only did that where no repairs had been done.

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PostPosted: Sun Mar 13, 2011 5:20 pm 
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ok, the deal is that if you just use etch primer on the bare metal patches, then put colour over it, It is going to sink back as the the colour dries. It is perfectly posible and perfectly fine, except for the sink back. Thats why you use a 2pak primer/surfacer over the top of the etch. Because it has a hardener in it, It will lock down as it dries, so it will stop further sink back.
So: First Etch prime , scuff back, Then Put a Primer/Surfacer(putty), rub back smooth, then paint.
Then you'll avoid it looking rubbish in a months time. :wink:

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PostPosted: Sun Mar 13, 2011 7:45 pm 
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Whatever you do, just dont rush it. Believe me, its so tempting to do it quickly and have your baby back on the road but in the long it'ss be worth the extra time.

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PostPosted: Sun Mar 13, 2011 7:54 pm 
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GT mowog wrote:
adamstuart wrote:
Thanks GT, but isn't that timeline in regards to how to wait until you put your filler over the top?
adamstuart wrote:
If i'm using etch primer on bare metal, but not using any spray putty;
How long do i need to leave the etch to shrink back before i lay colour on?

Or am i mixing up terms here, when i said not using spray putty, i meant not using surfacer.



.....Not sure, I'm not a painter, but ask Phat Kat, he'll know..........


miniDave and Mr Frail have it covered.

You really should use primer filler or primer surfacer... you can kind of get away with putting colour straight down on the etch... but its a gamble and you really won't get a good finish... the reason you use your primer filler (or spray putty then primer surfacer) is so that you have an chane to cover any light scratches or surface imperfections in the panel.

Like miniDave says, don't build your etch up anymore than a couple of light coats or you will end up with a really soft substrait for your colour and it will chip easy.

You can put your primer filler down on the etch about 3-4hours after you apply it.

No one really uses spray putty anymore... you can just use primer filler, its like a two in one... just as effective at both.


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PostPosted: Sun Mar 13, 2011 9:03 pm 
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Cheers guys, i wasnt going to rush it if the effects were going to be detrimental (might sound silly when we're talking about paint prep).

Was just enquiring about how crucial the surfacer stage was, since, lets be honest:

My moke won't be a show pony.

PS. PK, i'm painting acrylic, i presume the 3-4 hours between etch and primer filler isn't affected by acrylic/2pak?

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 Post subject:
PostPosted: Sun Mar 13, 2011 9:07 pm 
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adamstuart wrote:
PS. PK, i'm painting acrylic, i presume the 3-4 hours between etch and primer filler isn't affected by acrylic/2pak?


No difference :)


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PostPosted: Sun Mar 13, 2011 9:07 pm 
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adamstuart wrote:

My moke won't be a show pony.


It wont???

:lol: :lol: :lol:

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PostPosted: Sun Mar 13, 2011 9:11 pm 
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mattsmadmini wrote:
adamstuart wrote:

My moke won't be a show pony.


It wont???

:lol: :lol: :lol:


Well, it's not Samm's moke, but it ain't not hoodride either (wish it was - where do the roofracks go?)

PS matty
Should be priming tomorrow at the mokes house

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