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Author Topic: Finishing plastic  (Read 3925 times)

chris gillespie

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Finishing plastic
« on: July 20, 2013, 10:41:39 AM »

What do you guys recommend to finish plastic.
 
I have a plastic hull, probably abs but is thin and floppy could be styrene. It has some dents in it, the super structure has been made by a butcher and needs a severe tidy up, some large gaps, tons of glue snotters.
 
Due to the thin thickness of the plastic, sanding would have to be kept to a minimum id assume ?
 
So iam asking for best filler for plastic, ive ordered some green stuff, but never used it. I have revo but id rather not use that as it melts the surrounding area aswell as filling. I have dolphin glaze which is superb for fibreglass finish, but probably wouldnt stick too well.
 
Is there a cleaner that would dilute the glue snotters im assuming is cyano.....obviously not damage the plastic.
 
Thanks for your help
 
 

essex2visuvesi

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Re: Finishing plastic
« Reply #1 on: July 20, 2013, 10:51:55 AM »

I find revel plastic to be quite effective on plastic kits. Also squadron putty is good. You can find both at Cornwall model boats website.
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chris gillespie

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Re: Finishing plastic
« Reply #2 on: July 20, 2013, 11:19:38 AM »

Cheers Essex
 
ill look up squadron putty...
 
I also have soem badly scratched tinted plastic.....i was thinking a good clean, perhaps a quick going over with solvent to rub in the worst of the gaps, re clean then maybe some varnish to restore sheen...( maybe crazy idea i dunno lol  :embarrassed:  ) only alternative i can think of is to maybe buy window tint and stick it on....hopefully there is a smart answer out there.
 
cheers
 
 

Subculture

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Re: Finishing plastic
« Reply #3 on: July 20, 2013, 12:09:33 PM »

Dolphin glaze or any polyester putty (car filler) sticks very well to plastic hulls. Just key the surface with some 150-250 grit paper before application.

For the scratched tinted plastic, it dpends what the plastic is. PMMA/acrylic/perspex, will respond well to a light scrape, polish with successive grades of wet and dry down to about 1500 grit then compound with some Faraclea or T-cut. Some other clear plastics like polycarbonate or PVC don't polish as well, and you may find it impossible to polish the damage out. Do not use solvent on any of these plastics. I recommend replacing the plastic if possible.

Stavros

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Re: Finishing plastic
« Reply #4 on: July 20, 2013, 04:23:42 PM »

Ref cyno on plastic ...get a SHARP chisel and simply scrape off taking GREAT care obviously.

Ref Filler 80 grit the use Easy light or Top Stop this sticks well to plastic....dont bother with P38 load of .............well otyhers will of course contradict me BUT I do use both fillers on a daily basis so I know what works and doesnt !!!!!!!!!

There is some Cyno debonder never used it maybee someone on here has and can tell us what it is like


Dave

PS read my thread on fillers and painting



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vnkiwi

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Re: Finishing plastic
« Reply #5 on: July 20, 2013, 05:04:36 PM »

For the tinted plastic, do as 'subculture' suggests then coat with the original "Johnsons Clear floor polish", (believe they changed the formula at some stage) its a clear very thin self leveling liquid acrylic which plastic modellers us on clear plastic parts. I have used it on all my clear model canopys, as well as the full size car headlight lenses to get rid of the 'yellowing', which is the surface aging under our harsh uv in NZ. Sand off with 1000 or finer wet and dry to an even frost, one coat of clear, "problem solvered", as they say. Been there 4 years, still lookin' good.
cheers
vnkiwi
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Howard

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Re: Finishing plastic
« Reply #6 on: July 20, 2013, 05:27:50 PM »

hi,Chis,
for the plastic never sand use a  wood workers cabnet scraper, As for the clear plastic very fine emery cloth then tooth paste and auto glim car polish an buff up with old denim (old pace of jeans) the as said before johnsons floor polish was called klear now called future I think last time I saw it was in wilko,s 2/3 a bottle will last you and your friends the rest of your life, and that's if your in your twenty's.
                            Regards Howard.
 
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Stavros

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Re: Finishing plastic
« Reply #7 on: July 20, 2013, 06:03:40 PM »

Why on Earth do you state never sand plastic............only use a carpenters scraper sorry to say this but UTTER POPYCOCK

Plastic CAN be sanded it is the only and PROPER way to key the surface prior to the application of Paint......I prepard plastics of all types on a daily basis using DA sanding discs and scothbrite pads prior to painting and believe you me so do Hundreds of bodyshops...A Carpenter scraper can and WILL in the wrong hands cause so much damage to a surface.the it could very well need filler all over a plastic hull,Dry or even wet sanding will NOT .....

Dave
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chris gillespie

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Re: Finishing plastic
« Reply #8 on: July 20, 2013, 06:14:43 PM »

Thanks guys much to consider.
 
I cant remember where i saw it Stavros, but you recommend some plastic pre primer stuff.....that is the best bond to plastic then primer....
 
Typical you look at hundred of threads and go woow thats good info ill need to remember that for later....later comes and your like for france sake what thread was that again..lol :-)
 
So the tinted plastic, is a brown colour the butcher has also been there, no masking etc and deep scratches.......so the upshot is
 
Clean....sand 600 ish or emry cloth......toothpaste ? {:-{ ......tcut or auto glim.....buff with denim....johnsons floor polish
 
do you buff of the johnson floor polish or leave it to dry and seal
 
 

Stavros

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Re: Finishing plastic
« Reply #9 on: July 20, 2013, 06:21:44 PM »

Go to Halfords and buy some PLASTIC primer give it a couple of coats and then if you have use it put some High build primer on top of it with no probs at all


Dave
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vnkiwi

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Re: Finishing plastic
« Reply #10 on: July 20, 2013, 09:41:43 PM »

The 'Johnson's" (Clear/Future) is not a polish - its a clear acrylic gloss.
Had my 500ml bottle 5 years, use it all the time for all sorts of modelling and scratches on the family cars plastic lenses, And it still looks like a full bottle. Will be a family 'airloom' to pass to the grandkids at this rate, and still be more than 3/4 full.
For the rest, Stavros has it covered, know from my own days helping in the paint & panel shop, years ago.
cheers
vnkiwi
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Subculture

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Re: Finishing plastic
« Reply #11 on: July 20, 2013, 09:44:24 PM »

Toothpaste is a mild abrasive (otherwise it wouldn't clean the plaque off your pearlies). Not quite as strong as other compounds, but it will work.

Howard

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Re: Finishing plastic
« Reply #12 on: July 20, 2013, 09:54:15 PM »

Sorry Dave,(stavros) I miss read I ment joints after glueing not prep for painting I rub with with very fine sand paper or scotch bite and wipe with panal wipe hope this is a better answer and am doing it right as for Johnsons Klear or Future its not called  clear you can spray it brush it  or dip it the more coats the more glossy it will look.
                      Regards Howard.
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Stavros

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Re: Finishing plastic
« Reply #13 on: July 20, 2013, 10:15:06 PM »

AH HA that makes sense Howard I see were you are coming from hope no offence taken as certantly none meant


Dave
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chris gillespie

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Re: Finishing plastic
« Reply #14 on: July 22, 2013, 06:10:43 PM »

thanks very much guys
 
incidentally i bought a tube of 3m acryl red glazing putty, i was hoping for blue but this is meant to be decent stuff.
 
Im assuming this is also good for plastic filling,
 
cheers

Subculture

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Re: Finishing plastic
« Reply #15 on: July 22, 2013, 06:24:13 PM »

It's only suitable for very minor filling, like sand scuffs and pinholes in other fillers, prior to priming, don't use it for filling large areas, as it takes ages to dry, and the shrinkage is much greater than two part fillers. It also has much lower strength.

chris gillespie

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Re: Finishing plastic
« Reply #16 on: July 22, 2013, 08:01:05 PM »

Cheers Subculture
 
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Subculture

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Re: Finishing plastic
« Reply #17 on: July 22, 2013, 08:22:52 PM »

No worries.

Here are the fillers I use, the only one not pictured is Milliput, which I very occasionally use for small areas where strength is important.

From left to right Upol fantastic, a nice easy to spread and sand two part polyester filler of medium consistency (like peanut butter), ideal for filling large and small areas.

Upol Dolphin Glaze, a very thin and runny filler (think ketchup or salad cream), which you can spread over coarser fillers to cover pinholes or brush into corners for blending. Once again two part polyester based.

3M acryl red, a single part air dry putty, for filling very minor scratches pinholes etc. prior to priming and also for fixing blemishes post priming.

Reactive resins Easy Fair, a two part epoxy filler. Much stronger than the polyester fillers, and fully waterproof. It's also much more expensive, a little more tricky to spread smoothly, and takes a little more effort to sand. Also takes a lot longer to dry- you need to leave it overnight ideally. It's very good for corrective work on epoxy and polyester hulls, and is used in the 1:1 boat industry. For most jobs I prefer the polyester putties however.

 

chris gillespie

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Re: Finishing plastic
« Reply #18 on: July 23, 2013, 06:09:05 PM »

Thanks for sharing
 
I love dolphin glaze, well apart from when its turning to crispy cakes when i needed only 5 seconds more  %)
 
 
Incidentally what is the best approach to removing primer or paint from a plastic or fibreglass hull ? cheers
 
I have tried fairy power spray on a number of paint jobs......i dont get it...it just doesnt work for me

Subculture

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Re: Finishing plastic
« Reply #19 on: July 23, 2013, 06:38:59 PM »

I find Dolphin Glaze does 'kick' very quickly, so you have to work fast with it, and only mix small quantities at a time. i sometimes mix a little with the Fantastic to get an inbetween consistency and that works very well for me.

Regarding fairy power spray, I've seen this recommended a few times on this forum, haven't used that exact product myself, but used similar products based on oven cleaners (Mr Muscle etc.). They're all a fairly diluted mix of caustic soda based chemicals, very good at removing oil based paints like your Humbrols etc. Not so good for tougher coatings like cellulose and lexan paints, and probably won't touch anything two-pack based, which are essentially resins. I do find it helps if you rub the paint down a little first, and you do need to leave it on for a while to do its work.

A stronger caustic solution would work better, and the chemicals can be purchased cheaply from ebay etc.

But it requires care when using this stuff, incorrect use can result in splashes, and this stuff attacks skin, flesh and eyes with tenacity. So be careful.

chris gillespie

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Re: Finishing plastic
« Reply #20 on: July 23, 2013, 07:58:00 PM »

Thanks again Mr Culture
 
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Subculture

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Re: Finishing plastic
« Reply #21 on: July 23, 2013, 09:28:10 PM »

If you want a highly effective paint stripper, then you might want to give this one a try- http://www.wmbarr.com/citristrip/default.aspx

That should deal with any paint.

chris gillespie

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Re: Finishing plastic
« Reply #22 on: July 24, 2013, 09:52:19 PM »

Thanks again Subculture
 
So ive tried to find some Johnsons Klear..now defunt.....what is the closest alternative ?.....some modellers think the new incarnation pledge klear is rubbish.
 
I could wait for ebay, but if you know of a good alternative to fixing window plastic, again id appreciate it very much
 
cheers
 
Chris

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Re: Finishing plastic
« Reply #23 on: July 24, 2013, 11:12:32 PM »

Sorry I haven't used that. Is it single part or twin part coating?

chris gillespie

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Re: Finishing plastic
« Reply #24 on: July 25, 2013, 04:15:47 PM »

i think its a single self levelling acrylic, it was mentioned early in this thread
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