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Author Topic: Paint?  (Read 9204 times)

tigertiger

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Re: Paint?
« Reply #25 on: December 10, 2006, 03:43:57 AM »

FLJ's comments on the thickness of paint as supplied struck a chord as you never seem to quite know when you open a tin how thick it will be or the degree of covering power. This seems to apply to acrylics as well as enamels. Presumably it's something to do with the nature of the pigments?

Yes, I've found red and white (acrylic and enamel, the latter less so) to be capable of a certain amount of colour but seem to have no effect after 3-4 coats. I thought it was me being picky.  ???

Doug

Doug
The you mentioned red and white. These two colours are effected by the coulur of the primer that is used, big style.
I think that for both you need white primer to be effective.

But I am sure womeone will correct me. ;)
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dougal99

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Re: Paint?
« Reply #26 on: December 10, 2006, 06:02:23 PM »

Tigertiger

you are probably right but I would expect any colour to get a little more solid with each coat regardless of the undercoat colour (the final colour would depend on the undercoat I'm sure). Maybe it's me ...  ;D

Doug
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FullLeatherJacket

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Re: Paint?
« Reply #27 on: December 10, 2006, 11:37:12 PM »

Doug
From my own experience I'm with TT on this one i.e. final colour is seriously affected by primer colour. If you're still glueing that Sentinel kit together then please use grey plastic primer for the upper works when you get to that stage. It's fine for both the grey superstructure and the green deck, whereas red oxide is the obvious choice for below the W/L. I've built two of these and it worked for me, but suit yourself, matey - nowt's written in stone.
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tigertiger

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Re: Paint?
« Reply #28 on: December 13, 2006, 03:04:31 AM »

...you are probably right but I would expect any colour to get a little more solid with each coat regardless of the undercoat colour (the final colour would depend on the undercoat I'm sure).

I thought so too, but when I was patching my car i found that a dark primer caused an ugly shadowing  ???that did not disapear quickly as I added may coats of paint :-[

I think maybe some paints are slightly transluscent. Red especailly so. Maybe more than white.
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ambernblu

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Re: Paint?
« Reply #29 on: December 13, 2006, 07:56:39 AM »


I've always understood grey to be the primer for use under red. Can't remember the company I used now, but they wouldn't guarantee the lasting quality of the paint (it was for exterior use - window sills and such!) unless I used their grey undercoat for the red (which did look extremely translucent too!) But it worked a treat.

It may not however be a strict rule across the painting world, but then again, a lot of us use Halfords acrylic grey primer and then  slap red hull paint over that - can't remember ever having a problem doing that before! So maybe grey it is then!  ;)
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FullLeatherJacket

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Re: Paint?
« Reply #30 on: December 13, 2006, 09:19:08 AM »

Admiral Ambernblu
Yeah - maybe grey is the best colour for primer under red......in which case I wonder what the heck red primer is for ??? . Anyroad up, me duck, lazy types like me use Halfords red oxide primer below the boot topping and just spray it afterwards with clear satin. It looks enough like anti-fouling red to fool most punters.............suit yourself  ;).
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ambernblu

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Re: Paint?
« Reply #31 on: December 13, 2006, 09:31:42 AM »

Admiral Ambernblu
Yeah - maybe grey is the best colour for primer under red......in which case I wonder what the heck red primer is for ??? . Anyroad up, me duck, lazy types like me use Halfords red oxide primer below the boot topping and just spray it afterwards with clear satin. Less work; less paint, and it looks enough like anti-fouling red to fool most punters.............suit yourself  ;).

Sounds almost like a Mansfield 'eh-yup me duck!' there FLJ?? Yep, you are right, have got red oxide primer currently on my Cossack lower hull and I'm probably going to just give her another coat of that before the varnish goes on - its an excellent alternative and will do fine, just as you say!  ;) I'm planning on doing the same on my Manxman too!

What I mentioned about that primer was something that I had not given any thought to previously, just that that particular paint manufacturer (as I think some others actually do) specified their grey primer under their red and made it quite a guarantee of longevity of the paint finish too!

Cheers, Brian
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FullLeatherJacket

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Re: Paint?
« Reply #32 on: December 13, 2006, 09:50:32 AM »

Admiral

Not quite Mansfield, but go 14 miles south and you've got me bang to rights.

BTW all of the GRP hulls I use are finished in white gelcoat. Maybe this makes a difference, too. I gave Humbrol Hull Red enamel a try once but I thought it looked horrible, so off it came and back to Rattle Can Red.

I'm surprised any paint manufacturer would guarantee the longevity of their product, given the appalling examples of surface preparation that I've come across over the years of decorating houses. You know, newspaper stuffed into cracks in window frames, putty used as wood filler, Polyfilla an inch thick etc etc.

Being a modeller somehow makes me take greater care over decorating...............but I'm going way off thread. Sorry!
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tigertiger

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Re: Paint?
« Reply #33 on: December 13, 2006, 12:12:24 PM »

......in which case I wonder what the heck red primer is for ???

I think it is an oxide primer suitable for bare metal. The colour is incidental and is not designed as a primer for red paint.
It was the red oxide primer that was giving me such awful shadowing with the red paint I mentioned above.
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rats

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Re: Paint?
« Reply #34 on: December 13, 2006, 12:45:07 PM »

If you were using car type acrylics on say a tug, what  would be the best primer be for the wooden bulwarks and deck ?

         cheers rats
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tigertiger

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Re: Paint?
« Reply #35 on: December 13, 2006, 01:02:25 PM »

If you were using car type acrylics on say a tug, what  would be the best primer be for the wooden bulwarks and deck ?

         cheers rats

Again, I am no expert, but I will be using wood primer on my woodwork. I have yet to decied on the best topcoat.
I will use acrylics on my plastic hull.
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ambernblu

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Re: Paint?
« Reply #36 on: December 13, 2006, 03:01:42 PM »

Not quite Mansfield, but go 14 miles south and you've got me bang to rights.

I'm surprised any paint manufacturer would guarantee the longevity of their product, given the appalling examples of surface preparation that I've come across over the years of decorating houses.

FLJ... You will have understood the 'mighty Stags' reference then(!!) - although (unfortunately) not-so-mighty is much more appropriate at the moment - but then the same could be said for the rest of Nottinghamshire's footy teams too eh?

It was Akzo's Sandtex red that needed the special attention - not that it was much better for the said attention!  ;D Their black however was superb and went on anyhow, anywhere - and its still there well after the 6 years guaranteed protection period the company offered!

As for painting model boats, I often wonder if anyone takes into account the weight they are applying to their model as they are happily brushing, spraying, airbrushing away?? When you carry the full tin of paint out of the shop, I trust we are all aware that its the paint inside that weighs so much, not just the packaging (the tin!)

Rats - Priming wood, yes, I would say use a decent weatherproof wood undercoat/primer - I use it especially for any bare plywood, balsa areas - particularly inside the hull - well, you never know do you?   :)

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rats

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Re: Paint?
« Reply #37 on: December 13, 2006, 03:58:32 PM »

 Thanks for your answers : the reason I ask is that I bought some "Unibond Adhesive and Sealer" for just such a purpose but when I got it home and read the tin ! it says it should not be overpainted with water based paints - I am not sure if Halfords Acrylic range (or any other for that matter) contains water ?
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DickyD

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Re: Paint?
« Reply #38 on: December 13, 2006, 04:44:08 PM »


From the Oxford English Dictionary and I quote

acrylic

  • adjective of or relating to polymers of acrylic acid, an organic acid used in making synthetic resins.

  • noun acrylic paint or textile fabric.

  — ORIGIN from Latin acer ‘pungent’ + oleum ‘oil’.

No water?

Richard ;)

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rats

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Re: Paint?
« Reply #39 on: December 13, 2006, 04:49:21 PM »

Cheers ! but Humbrol / Tamiya acrylic paints are water based as far as I know ?
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ambernblu

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Re: Paint?
« Reply #40 on: December 13, 2006, 05:20:53 PM »

For the record, acrylic paint is composed of pigments in a polymer emulsion. The pigments (non-water-soluble coloured powders) are incorporated into a liquid plastic substance (polymer resin) that's dissolved and mixed with water. When the paint is applied to a surface, the solvent (water) evaporates, and the binder (polymer) forms a transparent film that holds the pigments. The drying time, or water evaporation rate, varies according to the surrounding temperature and humidity. Once dry, polymer resins are waterproof and flexible and are of a type of plastic developed not to break down, so a high-quality polymer combined with a high enough concentration of pigments will ensure a long-lived paint film.

Acrylic colours and mediums should not be mixed with turpentine or oil; however, you can use oil paint to paint over acrylics once they are dry. It is possible to begin your work by applying a base coat of acrylic and then continue using oil based materials, but remember not to make the base too smooth - and also that the reverse won't work... i.e. acrylic cannot be used to paint over an oil base.

 

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FullLeatherJacket

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Re: Paint?
« Reply #41 on: December 13, 2006, 05:28:16 PM »

Rats
I think Unibond is intended mainly for the building trade who use it for all manner of things e.g. sizing newly-plastered walls, stabilizing old plaster before a new skimming coat, plasticising mortar. It looks and smells very much like PVA adhesive - i.e. wood glue. I don't know how it would react to being painted with a water-based paint but I'd go with the manufacturer's warning if the decision were mine.
For priming bare wood I've always used a solvent-based thingy of one sort or another. I've found that cellulose dope or sanding sealer is great if you don't need the grain to show through; thinned polyurethane varnish or proper coating epoxy/polyester resins are better if you want a final wood-grained finish. I have seen some stunning results using thinned polyurethane but the one which springs to mind had about twenty coats of the stuff, all rubbed down in between. It's a slipper launch which won Best of Show at Warwick a couple of years ago; I'm sure there's a few pictures of it on the main Mayhem site. Gorgeous but a lot of elbow grease involved.
I've heard that some of the quick-drying undercoats are also suitable as they set up quickly, sand easily and clean up with water. I don't know if they'd stand up to constant immersion but how long do you leave your model in the water anyway?
The thorny topic of acrylics won't go away. From my experience Tamiya and Humbrol "acrylics" thin and clean up with water, whereas Halfords "acrylic" aerosols are quite definitely solvent-based; just spray one and sniff if you're unsure which you have. It seems from what Admiral Ambernblu says that we've just got sloppy when referring to the Halfords stuff as "acrylic".
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ambernblu

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Re: Paint?
« Reply #42 on: December 13, 2006, 05:52:07 PM »

The thorny topic of acrylics won't go away. From my experience Tamiya and Humbrol "acrylics" thin and clean up with water, whereas Halfords "acrylic" aerosols are quite definitely solvent-based; just spray one and sniff if you're unsure which you have. It seems from what Admiral Ambernblu says that we've just got sloppy when referring to the Halfords stuff as "acrylic".

FLJ... I think we would need to obtain a statement from Halfords with regard to the paint's chemistry - I've just checked one of their primer cans and it clearly states it is an 'advanced acrylic' - but yet that by definition of the hazard warnings, it is a highly flammable (UN1950) solvent based paint!
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rats

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Re: Paint?
« Reply #43 on: December 13, 2006, 06:34:00 PM »

Thanks for your answers .I wont be using the Unibond - as FLJ suggests solvent based seems the better option.  Ambernblu that is the best explanation of acrylic paints - even I could understand it !

         cheers rats
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DickyD

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Re: Paint?
« Reply #44 on: December 13, 2006, 06:51:46 PM »

Uni Bond is a PVA solution and can be used as a wood glue, it is also used as a sealer and bonding agent by plasterers and screeders. It is not meant to be used as a primer for paint. 8)
I wont suggest what to use as a primer in your case but I tend to use Halfords myself.
All other types of paint I left behind when I retired from the building industry after 40 years.

Richard :)
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DickyD

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Re: Paint?
« Reply #45 on: December 13, 2006, 06:54:37 PM »


Hi Brian
What is this thing you have about paint ?? ???

Richard ;)
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ambernblu

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Re: Paint?
« Reply #46 on: December 13, 2006, 08:24:53 PM »


Hi Brian
What is this thing you have about paint ?? ???

Richard ;)

Probably a lot of years in the chemical waste industry?   :D

Rats, thank you sir!

FLJ, I think I'll have to try and get hold of an MSDS on Halfords acrylic spray cans - see what's what!  ;)
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cbr900

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Re: Paint?
« Reply #47 on: December 15, 2006, 03:26:05 AM »

Richard, Rats, Brian And TT,

There is now an acrylic paint available which can be painted over with enamel, or the acrylic can be painted over enamel with no problems, as for the undercoat for red, white undercoat is the preferred colour as all other colours will make the red go darker, which is fine if you want a dark red....


Roy
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tigertiger

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Re: Paint?
« Reply #48 on: December 15, 2006, 10:20:07 AM »

When it is all done,

Is plasticote suitable to finish?
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DickyD

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Re: Paint?
« Reply #49 on: December 15, 2006, 10:36:34 AM »

Thats what I use. From Halfords.

Richard :)
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