Airbrush Primer & Paint for FUD and FXD Plastic Models?

Hello! Does anyone have specific airbrush primers and paints to recommend that have worked well on FUD and FXD plastic models? We have tried prepping the model surface with Bestine, then applying Vallejo acrylic primer, then applying Vallejo acrylic paint. Unfortunately, the primer and paint easily peels off. We started with acrylic paints due to concern that enamel paints would clog the airbrush. Does anyone use a different process, or have other primers and paints to recommend? Thank you for your help!

I ran into a similar problem with Tamiya acrylics. I'm thinking that Bestine is a petroleum based solvent and the items are known to be slightly porous, resulting in some residue. After the Bestine soak, I've been using some old Polly Scale Plastic Prep and seem to have decent adhesion with acrylics I spray Tamiya and PollyScale so far. You can also try a rinse with some warm water and Dawn dishwashing soap. Don't soak in acetone, it will soften and warp the thinner parts.
Like you, I'm still trying to figure out the best way to clean and prep for paint, it should be easier than it is!

I did one model with a spray primer for resin models. I didn't like that it was a rattle can, not much control. I don't recall the name, don't think there was any English on the can. Nasty stuff, but seemed to do the trick. Got it at a hobby shop, will try to get the name when I get home.

Hello! Thank you for passing along some ideas! It looks like that brand of Plastic Prep is no longer available, but I found another kind. Do you think this would be worth a try? http://www.amazon.com/SEM-38353-Plastic-Prep-oz/dp/B00B3HXWF O

Thanks again!

I'd try a soak in Dawn and follow with a rinse in 91% isopropyl alcohol. It will be cheaper and likely have the same end effect.

See my recent thread https://www.shapeways.com/forum/index.php?t=msg&th=32038 &start=0&

It may not be the cleaning... I believe it could be lack of complete cure, so that uncured resin is leaching out of the part, preventing good paint adhesion and cure.

Before or after cleaning, I'm trying a post cure operation of leaving the parts under a UV lamp for a while... you can also leave them outside in the sun for some time.

This is an interesting idea that we might try! Can you send a brand or model number for the kind of u/v lamp that you use? I've never purchased one before, so don't know much about them. Thank you!

I'm not sure what the *correct* spectrum is for curing this resin, but I used an 18" T8 sized flourescent tube in the UV-A band (advertised as a 375nm lamp). These fit in typical under cabinet fixtures. See the bulbs anywhere on the web, such as:
http://www.topbulb.com/sylvania-21623-f15t8-bl-15w-t8-fluore scent-blacklight

and read a little more about all the available types at:
http://www.topbulb.com/specialty-bulbs/ultraviolet


While I simply propped up my lamp a few inches over the parts, this fellow built a nice enclosed post cure chamber:
http://3dprint.com/27720/post-curing-lightbox-sla/

Another idea for any DIY'ers doing lots of this:

Gut an old microwave oven (one with a turn table), leaving the timer control and turn table;
Fill it up with the UV LED strips shown in the post above.

This is all very helpful!
What do you think about a smaller bulb, like this:

http://www.petmountain.com/product/reptile-incandescent-bulb s/11442-504972/zoo-med-zoo-med-repti-basking-spot-lamp-with- uva.html

Wish I could advise on that, but I have no idea about the relative UV outputs.

I wouldn't, that is basically a heat lamp with some UV spectrum thrown in. It'll give off more heat than UV.

Does anyone have recommendations for proximity of the plastic models to the UV bulb? What do you think is the proper distance? Also, any idea how long the models should be exposed for proper cure time?

Thank you!

I haven't done enough work to say that one thing is better than another... but it's working for me with the parts just a couple inches under the 15W fluorescent bulb, for about 1 hour.

My method for finishing off FUD and FXD is to soak them in acetone for a few minutes to remove the excess waxy support material, then rinse them in dishwashing detergent & water and dry them with compressed air. Then use baking soda in an air eraser (a miniature sandblaster that looks like an airbrush) to reduce the surface texture on the parts, and follow that with another detergent & water cleaning and compressed air dry. Then I would spray them with a coat or two of Tamiya Fine White Primer, which is a lacquer model paint that's available at hobby shops. For greater control of the paint coverage, I would sometimes decant the Tamiya primer from the spraycan and apply it to the parts with an airbrush. After these steps, you can use just about any paint on the FUD or FXD parts to provide the final finish.

Right, clean it and seal it.

But again, if my concern about there being uncured resin permeated throughout the body of the part is correct (and it IS correct in the case of SLA parts, so why wouldn't it be here for FUD?), then we'll all do well to zap the parts first with an extra dose of UV.

Leaving uncured resin inside the part cannot be good for long term durability or for long term paint adhesion... and it's easy to perform this "post cure".

On a Model RR forum I'm in it has been discussed at length and it seems the general concensus is that the current 3D printing process for FUD and FXD provide the proper amount of cure and no extra is required. I tried the UV cure under a small wattage blacklight (UV) at a distance of a few inches for about an hour and have not noticed any difference. Again, talking about FUD and FXD so I can't comment on other materials.
Be careful with acetone when using FUD or FXD, I left some pieces soaking for a while and they got very soft. Took days for them to harden up but areas were warped in the process. I think Bestine is the best bet though I really want to try Goo Gone as it is less expensive and a heck of a lot less toxic!

Thanks! Could you point me to that RR forum? I'd love to see the discussion.


PM

I'd like to but it's a closed Facebook group that gets over 100 new posts per day. This was at least a month back, so trying to find that thread would be an exercise in futility at best.

Facebook you say?
That confirms it, I'll be continuing with my UV post cure...