Morning all,
I'm attempting to make a shapeways/robex Russell. The print arrived nicely, I bathed it in white spirit for a few hours, thoroughly cleaned it and primed it using Humbrol spray primer. The primer took nicely and the next day I put my first coats on using Pheonix precision colours. A day later, and most of the enamel paint is still tacky, it's not adhered to the surface properly.
Now, this isn't the first time it's happened. I've had to strip it right back, sometimes multiple times. Does anyone know what the actual cause of this is? I'm suspecting the white spirit is absorbing into the plastic and leaking back out, preventing the enamel paint drying. However, I would have thought the acrylic primer would have prevented that. From memory, I have also tried it with enamel primer with the same result.
For reference, it's Robex fine plastic, and I only seem to have this problem on shapeways products.
Thanks
I thought you couldn't mix acrylic and enamal paints? First question I'd ask is the room temperature where its drying. That question would apply before and after cleaning the print. The primer should seal the print to if it was dry and the primer also dry when you applied the Precision paint then the fault would lie with the Precision paint. I've only ever used their paint a couple of times and ended up binning it.
Sorry I can't be of much help, though a few questions for you there!
I always use Halfords spray can primers. A loco like Russell I would want to use an airbrush for the maroon but I find all reds cover poorly so I would airbrush over Halfords Red oxide primer. In fact I did this just before Xmas for an H0 Shapeways Corpet Louvet that I put into simplified Cotes du Nord livery. After airbrushing Humbrol enamel 20, I left it 24 hours before masking to airbrush Humbrol enamel matt black, finisling with a couple of coats of sating varnish. Worked for me.
Thanks for your replies. To answer a few questions, the room temperature can vary. Although it should remain fairly constant , I left the print in a draw so it shouldn't have altered. This is actually the second room that I've had the same problem in. The previous one was far worse, and that was my first thought.
I've only had this problem with enamel paint, though I've used acrylic primer under enamel before. I know it's not ideal, but I changed my mind before. If it was the first time, I'd believe it was my choice of paints, but given I've had it with only enamel paint, I do think it's the print.
I thought the primer would seal it, as you say. The odd thing is, as I stripped the enamel, it took some acrylic with it. That says to me, the problem is under the primer, as that layer had definitely dried previously.
I decided on the cut down version of Russel, so I was using pea green precision paint. I'd love to do airbrushing but I've not got the ventilation anywhere to work it safely.
Thanks guys
Some years ago now, when 3D printing was very new, I had a very bad experience with enamels ( Humbrol , in this particular case ).
1, The paint soaked through the primer and stained the 3D material. This wasn't really a problem as nobody would ever see the discoloured print on the inside, but it was an indication that all was not well.
2. It took about 3 weeks to dry, when on other surfaces 6 hours was the norm.
So I have never used enamels on 3D prints ever since and I use acryllics exclusively on 3D prints now. I use a selection of Revell Aqua-Color & Games Workshop Citadel acryllics for brush painting & very occasionally Belton Molotow rattle can spray ( highly recommended for graffiti artists ).
I really like the Revell Aqua-Color range , but do take care with thinners & only use the Revell thinner, as again experience has shown that they react badly with generic thinners.
Garry
Quote from: Cyberman31 on January 19, 2021, 17:40
I decided on the cut down version of Russel...
Vandalism!
David.
Hi
Going back to the first post, I don't think soaking a model of any kind in white spirit is a good idea. Not all white spirits are of the same quality, some leave an oily residue and therefore acts as a release agent, exactly the opposite effect required. What does Shapeways recommend, I wonder, never having bought any of their products?
I have used many model mediums and used a cleaner such as Jif/Cif with warm water with an old toothbrush. To date, in 50 odd years, I have not experienced failing paint issues. Thorough rinsing to remove any traces of the cleaner and drying is essential. As mentioned above, temperature and humidity are very important. 20 degrees C or thereabouts and dry conditions outside is ok. Also allowing 24 hours between coats is a good idea and preferably sprayed. However thinned down brush paint can give a good finish, if you don't have spraying facility. Don't be too heavy handed with the primer, allowing drying time and definitely don't handle it unless with gloves. Fingerprints can also get you into trouble!!!
This may sound to be OTT, its a shame to spoil a lot of time, effort and skills if the paint falls off. Practice and patience will reap rewards. Good luck with your project. If I can be of help any more, please ask and let us know how you get on.
Best wishes, happy modelling.
Tod
https://support.shapeways.com/hc/en-us/articles/360033930173-Cleaning-and-painting-Fine-Detail-Plastic-models
Having said that, Tod, I've seen the white spirit method used by several dozen experienced modellers to clean Shapeways prints so I can't agree with you that it isn't a good idea. Though the methods can differ, the soak method or some others "scrub" the print with it (I assume using a toothbrush!).
Thanks - I've bookmarked that link.
I'll review my method after reading it fully...
My current method is - (jJust for the record, for those prints that arrive slightly "waxy":)
I put them in white spirit for 24 hours, then wash them in cold water with washing up liquid added and use a toothbrush to scrub them gently. I then rinse and let them dry at normal room temperature until completely dry - couple of days if necessary.
I then give the parts an undercoat of matt enamel - I use Humbrol, either black or grey - thinned down with white spirit.
I find this first coat dries fine and subsequent coats are also OK. I prefer to use enamels, which I apply thinned down and in as many coats as required.
And - I still use only brushes.
Whatever our thoughts and opinions of using white spirit are, if it works for you and not the cause of paint detaching, then that's good. The important message I offer is to ensure the cleaning agent, which ever is preferred, is to remove all traces of it before the primer is applied. I can only draw on what I was taught during my Naval apprenticeship 50+ years ago, (which painting many types of materials was part) and the subsequent years of work and hobby. Never too old to learn new things, I have a 3-D loco body ready for the paint shop, we shall see how it turns out!? I will have to wait until the weather warms up a bit, 7 degrees is far too low! My other disciplines will be applied of course.............
Happy modelling, keep safe and well.
Tod
Afternoon all,
I've just logged into the forum for the first time in a while and found this.
Thanks for your advice Tod, I'll keep it in mind for my next print work.
As for Russel, I spent a while cleaning it again and attempting to get the spirit off. When sniffed, there was an odour of white spirit off of it. I left it to dry for nearly a week near an open window, then reprinted and painted it later by layer, leaving 24 hours between. Whilst I can't remember what type of primer I used, this seems to have worked far better than my first attempt.
I used white spirit as that's the recommendation I remember from shapeways and a few other places, as it gets rid of the waxy residue the smoother prints tend to arrive with. It also turns the print from a slightly translucent colour to white which seems to be tougher.
If I buy any more then I may attempt a different cleaner but I think time is the key element. I didn't rush the first attempt but it doesn't hurt to wait a few more hours.