Decal Issues

[CyclesNoir]

Gotta funny problem with decals.

I use under clear coat style decals from AJ at Victory Circle Graphix, which my painters have always liked.

I'm playing with painting a prototype frame. Not planning to become a painter, just walking for a mile in their shoes to see what I learn.

As a one-time effort, I'm using rattle-cans. Primer/color/clear from Rustoleum plus some 2K clearcoat from Germany (working outside with appropriate protective gear).

I lay down clear and let it harden for a couple of days before applying decals. I've been careful about getting the decals down flat, without bubbles. The decals have sat several days prior to further clear coat, and remained flat on the tube.

When I lay down clear over the decals, and it starts to tack up, some of them start to wrinkle and/or bubble.

Any ideas why this is? How about methods to avoid this happening?

Let me know.

Cheers,

Rick G.
Cycles Noir

[John Winston]

shrinkage?

[progetto]

Thinners in clear reacting with decal?

[Rody]

Rick,

Without knowing the chemical makeup of the clear you are using, I can only offer some basic foundation information for ya that may help.

Assuming you have tested the clear on the decals prior to putting them on a frame without incident, here are some steps to try...

After laying down your clear over your base colors, allow it to harden and release the solvents per manufacturers recommendations.

Then, use 600 grit paper and lightly sand the entire frame to level and remove any nibs...this will also create a mechanical tooth for your decals and the next coat of clear.

Once sanded, blow off with filtered compressed air and wipe with with a surface prep to insure all oils are off of the base.

I believe that the Victory decals are vinyl based; take a hair dryer and gently warm the base under where the decals will be placed to help activate the adhesive once the graphic is applied. Lay the decal onto the warm tube with the centerline making lateral contact first and then work out from the center up and then down, firmly rubbing down and debasing the decal from the transfer sheet. Pay attention to work from the center out in all directions, so that there is even surface tension across the entire piece with no wrinkles, air trapping, etc...

When it comes time to apply the clear over top, lay the clear over the decals first in multiple thin layers, gently increasing the diameter of the area you are applying to to help build out from the decal slowly, eliminating potential shrinkage that can occur when a heavy application begins to harden.

Once the decals have a nice base built out from them, methodically clear the whole frame with a coat just heavy enough to flow out.

Allow to harden, sand, repeat :)

Good luck,

Rody

[CyclesNoir]

Thanks for the ideas. Now back to work. :)

[Dave Anderson]

Hi Rick,

That's an kind of an odd problem...especially since you are applying decals over the clear and then clearing over them with the same product. I use Victory Circle decals and have never had a similar problem. Is your clear a Urethane clear?

Wrinkling is usually caused by trapped solvents or repenetration......sometimes too fast of a reducer is used in the top coat product, or a faster drying product is used over a slower drying product. The faster drying product on top acts as a cap, sealing off the base layers, which just sits there. When another top coat is applied, it can penetrate down into the uncured layer below and cause wrinkling....especially if they are not fully compatible products. Rustoleum takes FOREVER to fully dry and so unless you let it sit for like a month before applying the clear coat, that could have something to do with it. The Metallics, if that is what you are using, dry quicker, but have even more compatibility issues. The interesting part is that its only the decals that are wrinkling.....but I still think that its probably a solvent pop issue.....since the decals were on there for a while before the additional clear was applied, its possible that they slowed down the curing of the layers below them. I would try letting the base coats dry longer before applying the clear, and/or let the clear dry longer before applying the decals. Trying another product may help as well. Its not nearly as durable as the typical urethane clear, but Rustoleum Crystal Clear enamel might provide a more compatible top coat for your test piece.

To give you an idea, I spray my urethane clear, force dry in an oven for 45 minutes, apply Victory Circle decals, and immediately re-clear and have never had a problem. Sometimes I even apply the decals directly to the base coat, depending on the base product that I am using (in fact, if I were using an old school enamel like Rustoleum, I would apply the decals before spraying the clear). However, I do know that my base coats are fully cured first, etc. HOK base products, for example, can wrinkle up, when applying additional clear coats, if not fully cured.... or if you have a sand through, or if the clear is a little thin in spots, or if the Moon isn't in the right phase! :-) :-) (Of Course, you would never apply decals directly to a HOK base...)

Dave

[CyclesNoir]

Dave,

Thanks for the insights. I suspect you're on target. Fortunately this isn't happening to all decals, just a few. I don't have an over, and don't want to heat decals to much, but may try some sun drying.

Cheers,

Rick

[Dave Anderson]

Dave,

Thanks for the insights. I suspect you're on target. Fortunately this isn't happening to all decals, just a few. I don't have an over, and don't want to heat decals to much, but may try some sun drying.

Cheers,

Rick

Cool.....what I meant by the oven part was that I don't have a problem with the decals even when I am recoating over them quickly. 45 min in the oven is about the same as letting the clear air dry overnight before decaling and reclearing. Also, I put the decals on a cold frame.

Anyway....just an FYI on what works for me.....ain't painting fun! :-)

Dave

[Rody]

Rick,

As you are experiencing, paint issues are difficult to diagnose when it is happening in front of you, let alone in an virtual environment on the net.

Shoot some pics of what's happening and the products you are using...definately will help in sussing out the issue.

FWIW, you don't need a fancy oven to cure your frames...a simple mdf box and a heat gun will do the job for what you need to achieve.

You will soon come to the realization that painting is a whole 'nother skill set that is much more difficult to master than fabrication. You will make many many (did I say many?) mistakes... beginning to achieve mastery is when you can fix them and no one but you knows it occurred.

cheers,

rody

[Dave Anderson]

You will soon come to the realization that painting is a whole 'nother skill set that is much more difficult to master than fabrication. You will make many many (did I say many?) mistakes... beginning to achieve mastery is when you can fix them and no one but you knows it occurred.

+100 !

[CyclesNoir]

Lots of good insights Rody and Dave!

I've already learned a lot, including an even greater appreciation of my painters!

After sanding back the clear and removing a decal, I touched up some of the paint. This morning, I set it on a stand in the sun and a bubble developed.

The bubble shrunk back to a wrinkled surface after sticking it with a pin. The bubble seemed like a thick skinned rubber balloon, rather than something cured on top and wet underneath. Lending credence to the idea that the Rustoleum is curing slowly.

Anyhow, I'm thinking at this point to just sand back to the raw frame and send it out for paint - unless something I've done might make it difficult for the painter to get a good finish.

Alternately, do you have a recommendation for a spraycan-based primer & color coat that would work better, cure quicker, cause fewer problems?

Thanks for your input!

I'll try to get pix after my ride.

[Doug Fattic]

Rick you’ve gotten excellent advice from Rody and Dave but I’m going to approach your problem from a different angle. I think it is possible your problem is that your clear is not compatible with your decals. Decals after all are a kind of paint/ink. I find House of Kolor urethane clear (not their polyurethane clear similar to Imron) to be less toxic to decals then the poly stuff. It sets up faster too so it is easier to apply multiple layers over decals for sanding. I always had more problems with decals wrinkling under Imron before I switched to H of K. I do use Imron as my final finish clears

[Dave Anderson]

Alternately, do you have a recommendation for a spraycan-based primer & color coat that would work better, cure quicker, cause fewer problems?

Actually, a fairly decent job can be done with Rustoleum for the occasional one off or etc. You just have to go slow and make sure every layer is fully cured before applying the next layer. Also, it goes on thick and rough and so sanding between every layer is also a must for a half way decent finish. Here is the handle of a compound bow that I painted 15+ years ago with Rustoleum. I just used their auto primer...sanded thoroughly...then one of their metallics...then multiple coats of Crystal Clear Enamel sanded between every coat. I never did a final cut and buff, so there is a little orange peel in the final...but its really not bad for a rattle can paint job..... Takes forever, but its possible.

Dave

[CyclesNoir]

Again, thanks to all for input. Lots of good information there.

I think that the black rustoleum was having some sort of curing issues. After piercing the paint bubbles, they laid down again. And the time in the sun seemed to harden up the paint. Using a pin, I was similarly able to vent gas from the deals and get them to lay down flat again. So that's all good,.

The deflated bubbles need a bit of sanding to smooth and blend them to surrounding.

Dave, I hear you re the rustoleum orange peel. It was part of what got me to experiment with the 2K epoxy. The latter is expensive, and there isn't much in a can. From where I've sanded back to repair an area, I'd say that the 2K doesn't adhere to the preceding layer as well, but but is tougher (less able to tear) than the rustoleum clear. The 2K also goes down smoother (perhaps in part because the spray tip on the can is much higher quality).

Net of this is I'm going to finish the bike myself, and use rustoleum and sandpaper to make it shine.

Cheers to all,

RG.

[Mark Kelly]

Sorry to come in so late but it took me a while to figure how to get here.

Here's how to prevent this from occurring in the first place. It depends on being able to predict the interaction between the polymer from which the decals are made and the solvents in the paint. There's a long hand and a short hand method for this.

The long hand method is to define the solvation space using the Hansen parameters for the polymer which give three dimensional co-ordinates and a radius of interaction and to see if the solvent is within this space. Fortunately, for the kinds of solvents used in paints, we can largely ignore two of the three dimensions in the Hansen model and use the short hand method which is the Hildebrand parameter.

First, you need to know the polymer from which the decal is made: from the above we can assume it's PVC (aka vinyl). Next, you look up the Hildebrand parameter for that polymer. In SI units for PVC it's 19.5.

Next, download the MSDS for the paint you are going to use - you haven't said which Rustoleum paint you used so I'm going to use the example of the automotive spray touch up. The MSDS is here

Look at the list of ingredients and work out which are the solvents - basically the next few ingredients after the propellant. Look up the Hildebrand parameter for anything greater than 5%. If you can't find the Hildebrand parameter, assume it is approximately equal to the Hansen d value.

Acetone 25% H = 19.7
Toluene 15% H=18.3
PM* acetate 15%. H= 18 approx
PG monobutyl ether 10%, H= 20 approx
n butyl acetate 10% H= 18 approx
methyl isobutyl ketone 10% H = 17 approx

total = 85% so a weighted average of the Hildebrand parameters is

(.25 * 19.7 + .15 * 18.3 + .15 * 18+ .1*20 + .1+18 + .1 * 17) / .85 which gives a final value of 18.7.

If this value is within 1 of the Hildebrand parameter for the polymer, you will get severe swelling and you would be best to find another paint. The further away the two numbers are, the better - a water based paint won't touch PVC because water has a parameter of 48.

It sounds long winded but it's easy in practice and it doesn't involve messing around with smelly chemicals.



* PM stands for Proplyene glycol monomethyl ether, that's why it gets abbreviated.