RC Groups

RC Groups
    Composites Fabrication
        Discussion 1k or 2k clear coat?or gel-coat?

#1 krikkens May 25, 2012 03:09 PM

1k or 2k clear coat?or gel-coat?
 
hi ,

what are the benefit's of 2k paint over 1k?

can i use a spray can to bring color on a 2k clear coated mold?

and what about gel-coat?

i guess there are diffrences in 2k clear coat , wich one to use?

i'm looking for high gloss ultra durable 2k clear..

special safety precautions need to be taken? just experimented with this one:


http://www.fishermotorfactors.co.uk/...cquer-hardener

my eyes got a bit irritated during spraying , maybe this stuff is to aggresive ? are there other options?


are there people who tried several stuff? what do they think? pro's , con's..

thanks

-kristof-

#2 heliwill10 May 26, 2012 05:17 PM

Humm..

2k is going to be more durable than a spray can. Not sure what your asking?

Quote:

can i use a spray can to bring color on a 2k clear coated mold?
Are you wanting to clear a mold then add spray paint over top? That might work or just buy a 2k paint.

I've had good luck with shop line ppg clear coats....

Safety.... You need gloves, respirator, and a well ventlated area, or paint outside.

#3 krikkens May 26, 2012 05:23 PM

Quote:

Originally Posted by heliwill10 (Post 21720375)
Humm..

2k is going to be more durable than a spray can. Not sure what your asking?



Are you wanting to clear a mold then add spray paint over top? That might work or just buy a 2k paint.

I've had good luck with shop line ppg clear coats....

Safety.... You need gloves, respirator, and a well ventlated area, or paint outside.

hi , i think you can add glasses to that list !

and the respirator should have a carbon filter, no?

yeah , i would like to use a spray can on the clear , and wan't a 2k clear for it's durabilty and a spray can color for it's simplicity , i only paint small area's with 2,3or 4 color's , it would be a pain to mix some up for such a small thing..

i know a gelcoat is used by many but i don't like the fact it yellow's...

-kristof-

#4 Jim.Thompson May 26, 2012 06:10 PM

What are you planning to spray paint Kristof?

#5 krikkens May 26, 2012 06:48 PM

1 Attachment(s)
Quote:

Originally Posted by Jimbello (Post 21720695)
What are you planning to spray paint Kristof?

a dlg wing , painted in the mold
this one has quit a bit of color on it , isually i just paint the wingtips

#6 Jim.Thompson May 26, 2012 07:55 PM

Kristof,

The reason that I asked was to get some impression of what the paint has to withstand etc.
On my slopers, I use all single pack acrylic lacquer. This is mainly due to the advantage of it's ease of touch up after dings etc. Slopers often have a hard life, as you no doubt know.
I have no experience with DLG's, but expect they fare much better in this regard. However, weight is your main concern is it not? In which case I assume you want fewer coats rather than more. One coat of either a good quality 2 pack or a single pack acrylic lacquer might be best choice for you? I'm guessing the latter would be very light, as it can go on very thin. Relatively less risk to the operator to spray. (than the 2 pack). Also cheaper and does not go off if you don't thin any more than what is required for the job. When thinned, it has a limited shelf life.

Jim.

#7 wyowindworks May 26, 2012 08:40 PM

2K vs. 1K Clear-coats

2K Clear-coats - Urethanes, Epoxy-based
+ More durable
+ More resistance to solvents
+ Often blocks UV rays that slow fiber and resin degradation
+ Can be rapid cured with IR light and hot-boxes (15 minutes)
+ Spray very nicely and flow out well (not necessary for in mold coatings)

- More expensive
- Required mixing, mixing cups, sticks for every use.
- Require gun cleaning after every use
- Often contain Iso's within the hardener that can be very harmful. Almost every manufacturer and instructor recommends a fresh air supply respirator rather than a canister respirator.
- Can take quite a while to cure before the layup can be performed if left at room temp.
- Can be more difficult to spray onto semi-permanents and wax only
- Can be heavier than 1K

1K Clear-coats
- Rattle cans, sprayable lacquers,
+ Inexpensive compare to 2K paints
+ Convenient if in rattle cans
+ Sprayable clear-coats can be left in gun for weeks if the gun and cup seal well. This cuts down on gun clean-up in a production setting.
+ Are easier and faster to apply on semi-permanents and wax only releases
+ Lacquers can set up at room temp and be ready for layup in 20 minutes.
+ Can be lighter than 2K
+ Typically aren't as harmful as 2K urethane formulations and only require a canister respirator.

- Little solvent resistence
- Less durable
- Typically offers no UV protection.
- Are more difficult to spary (not a problem for in mold coatings)


You can spray almost any color paint on top of a clear-coat. The color needs to be applied within the re-coat window. Many 1K clear-coats can be re-coated at anytime (after flashing has occurred). Most 2K clear-coats have a re-coat window of 1 to 24 hours depending on the cure velocity.

Gel-coats are not very favorable for DLGs or most RC aircraft use. Gel-coat needs to sprayed to required thickness to cure properly. If it's not applied thick enough you will end up with host of problems. Usually you need to spray it to a thickness of .010 to .020 to get a proper cure. Since DLG laminates are often thinner than this (wings, tails) the added weight can astronomical. Most of the clear-coat applications that I use on DLG fuses, for comparison, is less than .0005". It's also prone to micro-cracking because it's very brittle. Since gel-coat is polyester based there can be interface issues with epoxy resins. The gel-coat has an air-inhibited cure...meaning that the surface that exposed to the air will remain tacky and uncured. This is great for polyester layups since the layup resin will now chemically bond to and cure out the gel-coat. This tacky state can cause epoxy interface issues that requires some testing.

On DLG parts I typically use 1K lacquer based clear-coats out of a spray gun. I will typically only clean the gun once every two weeks when I'm in full production mode. The urethane based 2K clear-coats can be noticeably heavier and take more time to apply....at least on top of semi-permanent releases. You can get 2K urethane to be light but it takes some timely, careful techniques that require IR lamps or safe hot-boxes in the spraying area to control heat but evacuate the harmful fumes.

#8 Jim.Thompson May 27, 2012 12:08 AM

Quote:

Originally Posted by wyowindworks (Post 21721547)
2K vs. 1K Clear-coats

............................. I will typically only clean the gun once every two weeks when I'm in full production mode. .............

Is your gun gravity feed or a syphon type Adam?
Mine is syphon with an air vent (or course) on top of the pot. I wonder how long I could leave the paint in it?

Good report!

Jim.

#9 wyowindworks May 27, 2012 12:10 AM

Quote:

Originally Posted by Jimbello (Post 21722714)
Is your gun gravity feed or a syphon type Adam?
Mine is syphon with an air vent (or course) on top of the pot. I wonder how long I could leave the paint in it?

Good report!

Jim.

Jim, I have a gravity feed gun. There is a vent on top of the cup but it also a vent plug.

#10 Jim.Thompson May 27, 2012 12:14 AM

Quote:

Originally Posted by wyowindworks (Post 21722730)
Jim, I have a gravity feed gun. There is a vent on top of the cup but it also a vent plug.

Ahh! That is smart.

edit: Just by the way (off topic), I bought myself one of these little guns some time ago which is proving really good for detail work when the airbrush is just a bit too small.
http://www.ebay.com.au/itm/125-ml-Sp...item3a6c07a8a3

#11 krikkens May 27, 2012 01:45 AM

hi,

thank u for the help!

adam, i use spray can clear coat now but the main reason i wan't to move away from it is tha fact it ain't waterproof , water seems to go thru this...

gel-coat is used is used for dlg's sal-peter for instance , i contacted my supplier about this and he said it can be diluted 50% and you need much more harder .
it will need a cure at elevated temprature tough.

main advantage is it will be ready to lay-up for month's and the epoxy will stick to it well.

i didn't knew there was 1k for a spray gun , thanks ! it will reduce my pile of empty rattle can's every clean-up!

-kristof-

#12 krikkens May 27, 2012 02:48 AM

hi,

just pulled out a test part with 2k clear.

i think the clear is just to aggressive , i couldn't pull off the thick pva coating as it was bonded to the clear .

i couldn't even wash it of with warm water and soap , it remained feeling "greasy" .

-kristof-

#13 JIM CALDWELL A May 27, 2012 07:14 AM

Has anybody found a spray can clear that works well on 770NC??

#14 tom43004 May 27, 2012 09:17 AM

Jim,

With very light coats I've had good luck painting over 770-NC but heavier coats always bead up. I generally use the "painters touch" sold at HD for my quick color needs.

#15 wyowindworks May 27, 2012 10:50 AM

Quote:

Originally Posted by JIM CALDWELL A (Post 21724125)
Has anybody found a spray can clear that works well on 770NC??

Almost any spray can lacquer will work. The key is spraying the first coat very lightly, let it set (doesn't take long), then shooting a slightly heavier coat, let it set (doesn't take long), then a heavier coat. If you use a heavy coat right off the bat it will fish-eye.

The problem with rattle cans is that it's harder to control the light mist coats. With a gun you can set the stop on the product release needle so very little product is released from the gun. Then the next coat you can open the stop a little further and so on.

Adam


All times are GMT -5. The time now is 02:54 PM.