Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Painting, Finishing and Care. => Topic started by: Nordlys on April 19, 2013, 05:42:03 pm

Title: Paint finish set back
Post by: Nordlys on April 19, 2013, 05:42:03 pm
Over the last week or so I have been paint finishing my
new boat.
I have sprayed on 2 coats of primer, allowed to dry for 2 days or
more, then sprayed on 2 coats of finish gloss with 24hrs drying.
I had a few areas with paint runs where I had applied too much too
quickly.
 
Today I rubbed down these bits, and then also the whole boat with wet & dry.
It was now ready for a final top coat.
 
I have applied a final coat today, but this has come up quite wrinkly in places
which is very disappointing.?
I am using compatible paint and primer.
 
What could be the problem?
N
 
 
 
Title: Re: Paint finish set back
Post by: Sub driver on April 19, 2013, 05:55:19 pm
Probably too cold, temp needs to be a lot warmer than todays temps, a nice warm enviroment for model and paint works wonders.
Regards sub.
Title: Re: Paint finish set back
Post by: Nordlys on April 19, 2013, 06:11:08 pm
Sub,
Do you know, I've waited for weeks to start this painting work
and I somehow felt that it still was'nt warm enough -in fact today
the air temp has dropped from earlier this week.
 
I just got bored waiting around for so long!
I've always been aware that 50F is about the minimum for spraying.
Impatience!
Nord.....
Title: Re: Paint finish set back
Post by: hmsantrim on April 19, 2013, 06:27:41 pm
 
 Hi Sub.
         
 RE: temp needs to be a lot warmer than todays temps. Don`t know what its like where you are BUT...  We are all out in our shorts
  to-day up here in Glasgow..  had my lunch alfresco to-day.   {-)
 
                  Frank.
Title: Re: Paint finish set back
Post by: Nordlys on April 19, 2013, 06:34:14 pm
Posties go through the winter in shorts down here!
 
I think a few of them thought twice this winter tho'
I've only just surfaced.
N.....
 
Title: Re: Paint finish set back
Post by: essex2visuvesi on April 19, 2013, 06:40:39 pm
Weather here has crept into positive figures so its time to fire up the grilli :) (http://i717.photobucket.com/albums/ww173/prestonjjrtr/Smileys%20Summer/bth_bbq2.gif)


Its not only temperature you need to consider when spraying, also humidity can have an adverse effect on the paint finish
Title: Re: Paint finish set back
Post by: Nordlys on April 19, 2013, 06:47:16 pm
Hi Essex,
That leaves me with about 3 days per year to paint!
 
You can't grill the cod fillets until they thaw out you know!
Nordlys....
Title: Re: Paint finish set back
Post by: Stavros on April 19, 2013, 09:53:31 pm
MMMM Wet and Dry EH And I suppose you did it wet ??????
 
 
Dave
Title: Re: Paint finish set back
Post by: Nordlys on April 20, 2013, 08:37:32 am
Yes, wet I'm afraid!
Whats the likely outcome then Dave?
I have read your paint post but somehow overlooked the
rub down 'dry' bit!
N...
Title: Re: Paint finish set back
Post by: tt1 on April 20, 2013, 04:48:23 pm
Be interesting to know why WET and dry shouldn't be used wet ? - especially as its all ready been sealed with 2 coats of gloss.
                                    Regards, tony.
Title: Re: Paint finish set back
Post by: knoby on April 20, 2013, 05:47:16 pm
Primer is porous, so it absorbs moisture. That's why professional car painters only ever dry flat primer. We are talking about microscopic levels of moisture content here, which can be almost impossible to eradicate even after long drying periods, & most people paint the primer as soon as they have flatted it. You can leave it a day or two, but then the primer can skin over & cause adhesion problems. Moisture can also be a problem if you take a cold piece into a warm workshop, where condensation can form on the surface. Always best to let the work piece warm up to room temperature before painting..

Title: Re: Paint finish set back
Post by: tt1 on April 20, 2013, 07:07:26 pm
Cheers Knoby, but I thought Nordlys was flatting down runs after 2 coats of gloss had all ready dried.
                                    Regards, Tony.
Title: Re: Paint finish set back
Post by: knoby on April 20, 2013, 07:21:17 pm
yes, in this case it was gloss top coat he was rubbing down & that isn't affected in the same way as primer.
Flatting runs out can give rise to other problems. Firstly the paint inside the run will not be as dry as the surrounding area ( the paint in the run will retain more solvent). If whilst flatting the run out you go through the top coat on the surrounding area, this edge of paint can start to lift when you recoat the whole thing.
Also , when re-coating a newly painted surface, the solvent in the new paint can attack the older paint & cause it to react, especially if the temperature is low when the new coat is applied.

Title: Re: Paint finish set back
Post by: Stavros on April 20, 2013, 07:25:57 pm
Well you have hit the nail on the head lads allready.
 
Baisically it is a combination of moisture trapped under the gloss and also the subsiquent repaint.
 
Personally I would rub down the whole lot and start again rubbing down DRY
 
 
Dave
Title: Re: Paint finish set back
Post by: tt1 on April 21, 2013, 01:03:51 am
Cheeers gents  :-))  Regards, tony.
   Ooops ----- Sorry Nordly. didnt mean to hijack your thread,  :embarrassed:  Tony. :-))
Title: Re: Paint finish set back
Post by: Nordlys on April 21, 2013, 08:17:36 am
Well you have hit the nail on the head lads allready.
 
Baisically it is a combination of moisture trapped under the gloss and also the subsiquent repaint.
 
Personally I would rub down the whole lot and start again rubbing down DRY
 
 
Dave
Hello Dave,
I sort of pleased to read that you say rub down 'dry' and 'start again' as opposed to strip it all off!
I'm going to allow the paint to dry for a further couple of days then continue
with the final coat and then on to Lacquer at some point, after whenever!
 
Nord.
Title: Re: Paint finish set back
Post by: essex2visuvesi on April 21, 2013, 09:21:55 am
I would rub down dry as said but then once rubbed down leave it for a day or so just to ensure its completely dry, then start again with primer and top coat
Title: Re: Paint finish set back
Post by: Nordlys on April 21, 2013, 10:01:07 am
Interesting.
Primer again then topcoat? Didn't think of that combination at this
stage  - I was going to go ahead with a final top coat but
this could be a safer approach to achieving the desired final finish.
Decisions.....thanks.
Nord.
Title: Re: Paint finish set back
Post by: essex2visuvesi on April 21, 2013, 10:24:35 am
That's how I would do it.... might not be the correct way tho!


Also once you have finished rubbing down, clean the final dust etc off with a panel wipe
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_176921_langId_-1_categoryId_165495 (http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_176921_langId_-1_categoryId_165495)
1 wipe should be sufficient to clean an average sized hull


Once the surface has been cleaned DO NOT TOUCH IT as you will leave greasy finger marks (no matter how clean you think your hands are) and this can cause paint imperfections
Title: Re: Paint finish set back
Post by: Nordlys on April 21, 2013, 11:11:06 am
Thanks, I have the wipes from earlier painting attempts!
Just rubbed down hull again (dry) and left out in the sun to
harden off/dry completely.
N...