What clearcoat do you recommend?

General Composites Discussions Composites Talk
#1

Hi everyone,

I’m looking for a professional clearcoat to finish my parts. After a lot of trial and error i managed to overlay some parts for my car and I also made a few with resin infusion. Now I want to protect them from the elements, but a spray can from the diy-store is not an option, I tried it and it didn’t last very long. I don’t know a whole lot about clearcoats but this is what I want it to be:

-very good UV protection (no yellowing)
-somewhat elastic (so when I install & remove interior trim, the clearcoat doesn’t crack)
-NO ISOCYANATES (I don’t have the right protection)
-easy to use (not mixing 4 components in microscopic proportions)
-good adherence to carbon fibre (so it won’t peel off obviously)

Those are the most important I think. Price is not a huuuge factor, I just want it to be high quality

#2

Don’t know where you live but in the US I prefer PPG Concept clearcoats.

#3

I don’t know of any good ones that are iso free.

#4

I am also on the PPG side. I have a few different types but always find myself using the PPG. That and a nice gun will always make for a good clear coat. I like my Sata Dreamjet.

#5

If price is not a huge factor, GET A MASK!

Then you can use isocyanates / PU paint. This meets all your requests.

Spraying any other paint without a mask is russian roulette as well.

#6

House of Color UC35. very high quality stuff. excellent uv blockers. This is what most high end auto body guys are spraying on CF hoods and panels.

#7

I looked into using 2K paints for some motorcycle bodywork I’m making, and what I found was that there is a lot of misinformation out there. First up - there is no scientific data showing that isocyanates cause cancer. This seemed to be one of the biggest concerns that people have. But the fact is that anyone saying ISO’s cause cancer is making a false statement.

What ISO’s do cause is asthma-like symptoms. This has been stated by various government organisations and you can also find this in various safety studies, etc.

The reason I mention this is that you have to keep it all in context… Of course you shouldn’t spray 2K without a respirator. But the same is true for ANY kind of painting (like herman mentioned). Also welding, composites work, sanding etc. An appropriate respirator should be used for all those circumstances. There’s nothing special about 2K paint, the same precautions should be taken in many other types of work as well.

Now that those myths and facts are cleared up…

You can get ISO-certified half face masks from Gerson. (Gerson 2K disposable respirator £14.99 and I have this bookmarked for some reason, you may be able to lookup the specs directly from Gerson: http://www.gersonco.com/Products/8211P-Disposable-Dual-Cartridge-Respirator-OVP95---Medium----0871501B__0871501B.aspx ) This is the only manufacturer that seems to specifically mention that their masks can be used with ISO. The strange thing is, they use exactly the same filters, same specs etc. as all the other brands. So what gives? Why don’t 3M and all the others say you can use ISO paints with their half masks? It looks like they just don’t want the liability, because with disposable filters the only way you know it’s not working is if you smell the paint, at which time you’ve already inhaled those isocyanates.

To avoid that problem you just need to keep track of how long you’ve used the filters, and replace them before the specified usage time has elapsed. For example if the filters say that they last 20 hours of normal use, just change it after a day (8-10hrs or something) and you’ll be fine. Both the prefilter (for the actual paint/particles) and the organic vapor filter (for chemical stuff, ISO’s etc.) will need to be changed. (Of course be sure that you have the right kinds of filters. The particle filter should be easy, but I believe there are different grades of organic vapor filters.)

If you’re using filter based respirators, don’t paint in a closed room. It may seem like a good idea to keep dust out (and stop the paint/fumes/etc. from getting out) but that’s going to use up your filters much faster and you could probably easily overdo it and inhale some fumes. Not to mention that it would create a fairly explosive environment with all those fumes collecting…

It’s also worth noting that some areas have an outright ban on spraying isocyanates, check with your local council etc. etc. Also if you choose to spray in your home shed, be aware of anyone else who is around, for example the neighbour kids playing in the yard, the elderly lady working in her garden etc… they will not be protected if any paint/vapours reach them… (But these are entirely different issues to the safety equipment required.)

#8

Inaddition to this: Use A2 filters, and P2 or P3 filters for the particles, depending on the amount of dust expected.

When you are up to big jobs, use a power operated system, which gives you a nice breeze over the face, and easy breathing.

#9

Thanks a lot for the replies guys, for composite work I use this respirator: http://www.cjsafety.co.uk/wp-content/uploads/2011/09/4277.jpg , but it seems for spraying 2K most people have some kind of charcoal filter included in their mask, is this a back-up or something? Or what does it do more than those all in one filters?

I decided to make a mini spray booth, similar to a sandblasting booth, which has a light negative pressure inside. I only make small parts, so this way i can work dust-free and harmfull gasses will be directed outside.

does anyone have a specific recommendation for a ppg clearcoat that fits my criteria? (flexibility, uv resistence, good adherence) and how about the Omni brand paints, which are in the same ppg group, are they any good?

and last but not least, sice it’s only small parts i would use a hvlp mini gun like this berger http://www.tool-topia.net/images/products/ber8704.jpg again I don’t really know what to look for, do I need something more sophisticated?

again, thanks a lot for helping me out here guys, there is not a lot information about this topic, almost seems like some kind of black art :stuck_out_tongue:

#10

Does anyone use an adhesion promotor ?

#11

Wet sanding with 220 Grit to 600 Grit is what most people use prior to clear coating, not adhesion promotor.

#12

Hey Marcel,

Do you have more information about how you constructed your spray booth? How did you manage the negative pressure?

As for the HVLP spray guns, yeah they seem to be all the rage… but if you’re not doing much painting it may not be worth the cost. If you want to spend money you could also consider LVLP guns, even less overspray than HVLP. Personally I just bought a conventional gravity feed spray gun. I’m not doing much painting at all, so I’m not worried about wasted paint from overspray (only really a factor if you’d doing lots of painting). I haven’t used it yet though, but I’m sure it will be completely fine.

Also what do you mean by “small parts”? Those touch-up guns are really meant for small areas… you can probably check some vids on YouTube, see it in action & check if a mini gun will suit your requirements. (One persons idea of a small part could be very different to another.)

For the paint, I think surface preparation has more to do with adhesion than anything else? I also thought that all 2K has those qualities you want, flexibility & UV resistance. I mean look at car bumpers… they manage to get push in and rebound fine with no marks in the paint. I don’t think that manufacturers or repair shops use any specially formulated paints… in any case if you go to your local paint shop, or enquire wherever you intend to buy your paint I’m sure they can answer all these questions for you and recommend the best product.

#13

I’m constructing the spraying booth as we speak. I’ll make it out of plywood, with a plexi window and some sandblasting gloves. It will also feature a few lights and four 100W infra red bulbs to aid hardening. I’ll also paint the inside for a smooth, easy to clean, dust free surface. The negative pessure will be achieved by a small fan (2m²/minute) in the air outlet so if there is a small leak in my construction, it will suck in air instead of blowing clearcoat particles out.

About the spraying gun, I don’t really have to have HVLP, it just caught my eye beause it’s only 30€, and doesn’t use a lot of air. Would a 0.8-1.0 nozzle be fine? by small parts I mean interior trim, wing mirrors, etc.

#14

Ah, you really do mean small parts. Haha. I’ll need a bigger area so I’m going to section off a corner of my garage, trying to get ideas for how to setup the ventilation. I was thinking of a couple of fans, one blowing in and one blowing out (considering that I’ll be standing in there spraying).

For 30 Euro that doesn’t sound too bad, the mini guns probably do use less air. But compared to conventional they do require a higher rate of free air delivery (that’s the High Volume part). For small parts I’m sure you won’t need too large of a compressor. I would check with your paint supply shop about nozzle size, I’m not sure if nozzle sizes are different between full & mini guns, or if HVLP and conventional makes a difference either. Honestly if you go to a good paint shop, just let them know what you want to paint and what you’re thinking of using, they will give you good advice.