Eaglepilot2

Pardon my ignorance, but could someone explain how a model gets painted in the mold. I can't understand how this process is accomplished, and almost all ARF's are done this way. Just doesn't make sense how you can do this and get precise lines and color separation. The comp-arf eurosport even has what looks like blended colors. (sport version)

Thanks for any help.

Mike

rhklenke

My Feedback: (24)

Actually, the mold itself is painted (in mirror image) before the glass is layed in. The glass sticks to back side of the paint and lifts it out of the mold when the part is pulled. Actually, this type of technique has been done for "painting" other composite products like boats for some time before it made its way to models but it seems like the models have taken it to the next level in terms of the complexity of the available paint schemes...

Bob

ravill

My Feedback: (11)

Great post! I think "painting in the mold" should be called "placing seams on the model"

Raf

rhklenke

My Feedback: (24)

Well, yea, that's the problem. You paint and layup the right half of the fuselage in the mold, and then the left half. Then you trim the edges back to the molds, put some glue on the edges, (optional: stick the formers in either before or after), bolt the two molds together and put some reinforcing tape on the inside of the seam. Let the whole thing cure, and then pop the finished fuse out of the molds. The result is a fairly "rough" seam that you can't do much about because it surrounded by painted fiberglass. On a 40' boat, that seam isn't too visable, but on a 6' model it tends to stand out more. That's why some models have a part of the scheme that is painted "out of the molds" to cover the seams (i.e., I think that Ultra Bandit is done that way).

Bob

rcumember77

Just to add to Bob's great explanation, the mold is waxed and and a layer of PVA release agent or two is sprayed on to the mold after it is waxed. And that is how the paint does not stick to the mold.

I have tried this method a few times with varying results. The learning curve is steep, but the end result, well you've seen good examples.

Harley Condra

My Feedback: (4)

rcumember, Bob,
That is a good explanation of how to paint one solid color, and I have done it any number of times.

The BVM jet kits have a coat of PPG K36 primer on them. That's not gel coat like some people have stated countless times on RCU.

How do you do multiple colors? You sure can't stick any type of masking tape to PVA, and expect the PVA to stick. You can't hardly touch PVA without breaking it.

Here's my solution: Apply release agent to the mold. I prefer Airtech Release-All 30. PVA is not necessary, but adds a certain amount of insurance, and might make you feel better.

Before shooting any color in the mold, shoot a double-wet coat of clear, such as PPG 2021, or whatever clear you prefer on top of the release agent.
After the clear dries, shoot the multiple color scheme over the clear, using masking tape as required. As long as the tape is not very high tack, and you are very careful, it might not pull the clear away from the inner surface of the tool. The paint shouldn't need to be very heavy....the base color will go on last anyway. Most base colors are lighter than trim colors, so you won't be able to see through them to the darker trim colors. I have never done a multi color scheme inside a mold, but I have done single colors a number of times. lastly, make the wet lay-up over all of the colors.

Maybe they are using a high speed clear so they don't need to wait all day for the clear to dry......

Using a coat of clear as a barrier over the release agent (especially PVA) is the only way I think you could get away with multiple colors....especially in a complicated, crisply masked multiple color scheme..

I never have asked someone like BV just how the entire color scheme on an Ultra Bandit is done, but I do know that the seams are sanded, filled painted and polished out after the airplane is demolded. If you will take notice, look at the BVM website at the Ultra Bandit paint schemes, and you might notice that the entire fuselage butt line is painted top and bottom. There is no seam visible. Uncle Bob has been filling, painting and polishing them personally.

Anyone have any other ideas?

Harley Condra
BVM REP
JetCat REP

Ehab

My Feedback: (44)

The same "hide the mold line" technique that Harley is describing is used on the Bandit ARF. Looks like it is masked and painted afterwords, as a matter of fact, some the paint on the inlets came off when I removed the painter's masking tape ...just a little and it can't be seen... luckily. The multi color Bandit is really nice and it has sharp crisp lines between the colors. I am impressed with all these ARF's paint jobs coming out of China recently. I think it is only going to get more fancy!!!!!!!!

rcguy!

My Feedback: (69)

Is the Bandit ARF made in China? I thought Thailand?

Dave

AirPac Models

Bandit ARF is not made in China. You are correct, it's from Thailand.

For the joint seam, the BVM and new Skymaster ARF Plus are very thin. It almost just like a hair line. It's because the higher quality of mold. (also very high cost) For some companies, paint from out side the mold become most reasonable solution for the issue. It's might be a issue, but I don't feel it's a "problem" if the price is low. You pay what you got.

Ehab

My Feedback: (44)

I should have used the term "Asian" made.

Thomas B

My Feedback: (4)

I have heard that some types of wax work better with painting in the mold than others....it is really an art.

rhklenke

My Feedback: (24)

BV told me once that it took him awhile to figure out the technique and master it to the level he needed for his Ultra Bandit, so I'm sure that's the case...

Bob

digitech

My Feedback: (10)

aaaaaaaaa now it makes sense why we pay 5 grand for a arf....

Ehab

My Feedback: (44)

You mean over $10k for the UB

rhklenke

My Feedback: (24)

Well the $10k is because the UB is done in the US, and the seams are hand filled/sanded and painted outside the mold so they don't show like the KC and BC...

Bob

Eaglepilot2

Thanks guys for all the input. I can better understand it now, but I must confess I would need to actually see it done to really understand it. I just can't fathom how these guys do these great looking schemes with multi-colors and fading colors, all with precise lines and not to mention all of this has to be done in reverse i.e. (mirror image) These guys have got to be good to be able to do all that. If it is indeed done this way I am truly impressed and can some how understand the price. But wouldn't it be easier and less expensive to do it the traditional way??

Impressed,

Mike

Thomas B

My Feedback: (4)

Nope, Once you have the skills, it is easier to paint in the mold.

Remember, if the mold is perfect, the surface paint finish will be perfect...no dust, no bugs, no overspray, no paint layer buildups when colors change, no sanding scratches and more. Think about this one huge labor savings: no spraying or sanding of coats of primer.....

If you can live with the seam..and on some models, the seam is about a human hair wide...... the painting labor is about half of the labor of painting and finishing one outside the mold. and some schemes are, as mentioned in previous posts, designed for the seam to be sanded and easily painted in one color.

The main reason for painting in the mold is that most cash customers want things pre-done these days, and it is far cheaper than painting out of the mold.

kelly vallee

I'm starting to like this, I have heard of it and always wanted to try it. But, after put the clear, what type of paint do I use ( base coat ) or what. And what if I wanted to add stickers, can it also be done.