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Author Topic: Primer just not covering  (Read 2048 times)

TugCowboy

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Primer just not covering
« on: October 01, 2008, 04:22:43 PM »

Hi guys,

I'm currently in the middle of painting a plastic hull, which has been totally stripped back to its original plastic colour and painted with Halfords Grey primer.

Its had 5 good light coats now but there is still a blue band showing around the middle of the hull, about where the waterline is. The paint in this section just wouldn't totally strip back, I sanded for hours, used a plastic preparation cleaner and even tried a plastic-safe paint stripper, before washing the whole lot off and just painting over it.

The Grey simply isn't covering it even after the 5 coats. The hull is going to be antifoul red on the lower part, and then black on the upper section.

My question is this:

I'm going to use the Halfords Oxy-Red primer for the anti-foul, should I just try doing the red over the top all over, hoping that the darker colour would cover the underlining blue? or do I just keep sanding and priming with the grey until it goes (which would probably take about 10 coats at least looking at it)

I know I have prepared the hull properly for painting so I don't see that being the cause, I spent 3 days and a lot of hard work on it - it wasn't just a quick job I assure you.

Your help is appreciated.

Alex
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Guy Bagley

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Re: Primer just not covering
« Reply #1 on: October 01, 2008, 04:39:57 PM »

stavros is the man re paint application !!!
 he'll sort you out !


personally if you have a good application of primer on the area in question and as you say preparation is good, ie the surface is free of contamination, no grease, no oily marks, no previous  residue,  no nothing then i would be tempted to  try a light  coat of the red oxide...

(i presume the area affected is designed to be covered by the red oxide as per the plans/ design ?)

or are you 'extending ' the red oxide purely  to cover this potential trouble spot and then maybe adding the black top coat over the top  ?


a light covering will give an indication as to weather or not this blue band is going  to show through and worse case scenario is you have to rub back the light coat,   best case scenario is that the red oxide light coat is fine, and then build up the colour or add the black top coat  until the desired effect is complete !

 but hey what do i know ......
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TugCowboy

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Re: Primer just not covering
« Reply #2 on: October 01, 2008, 04:46:26 PM »


or are you 'extending ' the red oxide purely  to cover this potential trouble spot and then maybe adding the black top coat over the top  ?

I would have to extend it somewhat yes, this wouldn't worry me too much as its sold as a primer I assume it would cover up with a black quite well?

It just worries me a tad as normally the grey covers so well!

Alex
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Subculture

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Re: Primer just not covering
« Reply #3 on: October 01, 2008, 05:02:37 PM »

Sounds like something is bleeding through the primer, permanent markers can do this. A solvent based paint, like Halfords primer will react with stuff like that. You want a primer that can seal over difficult surfaces, or take it to a paint shop and have them whack a two-pack primer over it.

Andy

Stavros

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Re: Primer just not covering
« Reply #4 on: October 01, 2008, 05:45:06 PM »

Use some BLACK satin from Halfords then rub down then use the red oxide primer as antifouling.The black should but no guarantee seal the blue from comming through.What i want to know is was the hull blue or is it a waterline that has been marked with a blue pen,if that is the case then sorry but get the wetdry out and rub it off




Stavros


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Seaspray

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Re: Primer just not covering
« Reply #5 on: October 01, 2008, 06:44:40 PM »

Hi m8s
Clean and preparation  are the key to good jobs.

Need to try and get rid of the blue completely or find something to smother it (cover and seal) or find a compatable paint that will like to stick to the blue.

It being plastic I was going to say ,you should have no probs but the blue might have eaten into the hull. Again in that case a sealer is needed that will accept the plastic and the blue

Might be as Subculture says, paints don't like markers have you smelt some of them, when your using them.
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Stavros

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Re: Primer just not covering
« Reply #6 on: October 01, 2008, 10:18:15 PM »

As in previous posting black is the best sealer going


Stavros
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Klunk

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Re: Primer just not covering
« Reply #7 on: July 15, 2009, 04:32:54 PM »

try halfords plastic bumper primer, works well for me!!! Thats if you have wiped the boat down with soapy water and dried thoroughly, If in doubt use some alchol to clean it with up PLEASE test first to make sure any plastics do not melt!!!
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TugCowboy

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Re: Primer just not covering
« Reply #8 on: July 15, 2009, 06:53:57 PM »

Thanks for the reply (if a little late!) got it sorted now, as Stavros said I primed it in black and then sanded to give a good finish and it all worked out alright, it was the previous colour bleeding through, nothing I had put on myself.

Alex
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DickyD

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Re: Primer just not covering
« Reply #9 on: July 15, 2009, 08:44:50 PM »

Blue has always been the worst colour to paint over as it invariably shows through the new paint,

Same in house decorating you always need more coats to cover blue.
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