Prepping resin parts for chrome plating

[Hawk312]

Some of you are familiar with my saga, trying to get my resin casted wheels chrome plated. I have sent them out three times to a reputable plater, only to have them return with tiny bubbles all over them each time.

In my latest effort, I created the master, created a mold using no release agent on the master, casted a dozen or so wheels with no release agents used and heating the mold, removed the parts from the mold, mounted them, and shipped them off to be chromed. I have been using the Alumilite mold silicone and their casting resin as well. Both have been purchased withing the last six months. I am able to spray paint the resin castings without any issues, perfectly smooth. I can also use products like spaztix and have it come very close to chrome. However, the chroming always fails with the pitting, yellowing, and tin pin holes in the chrome.

I have been thinking about this, and have been searching the forum. Even though from start to finish I am not using a release agent, do I still need to use some type of degreaser on the parts before having them chromed because of the silicone mold? I see many people mentioning Wesleys bleche white. Since this is no longer available, is there something else I can use? I really need to get this working.

You guys who are getting your resin castings chromed, what is the method of your success?

Thanks.

[1930fordpickup]

Another company makes bleche white now. They sell it at Dollar General and other places. If you have not soaked them before you had them chromed last time I would try it to see if it makes a difference. Resin is porous and when they Vacuform the Chrome it may cause the pits.

Edited January 5, 2015 by 1930fordpickup

[Jeremy Jon]

Can you prime the parts in lacquer first Dave?

What does the plater advise as a base coat which you could apply?

Also, can you (PM if desired) which company you're using, I've been looking for some plastic/resin chrome plating work to be done, thanks!

[Art Anderson]

If you are seeing pits and bubbles in the plating on your resin, that sounds very much like tiny pinholes in your castings. From long experience, these can be caused by a couple of things: Air mixed into the resin when stirring it, or moisture contamination in the resin itself. Again, from my experience, the silicone in the rubber most likely is not the problem, as it's part of the chemistry of the rubber, not a coating on it.

You mention that your resin is perhaps 6 months old--that could well be the problem. Once opened, humidity in your surrounding air can get into the bottles, as the air in your room goes in to replace the volume of resin poured. That sounds to me to be the most likely cause, as air bubbles generally are much larger, and if next to the detail surface of the casting, where the tinier bubbles (CO2 gas) more than likely will be distributed throughout the castings (trick to find out: Take one of the wheels, whittle it apart with your Xacto knife to see.

Heating the molds really doesn't help, frankly, not with ordinary polyurethane resins such as Alumilite--that accelerates the kicking/curing of the resin enough to prevent any air bubbles from escaping from the detail surface (bottom of the mold cavity) which could well exacerbate your problem. Nor does putting the freshly poured molds into vacuum chamber--that simply expands any tiny air bubbles in the resin and the resin likely will start to set up before any of them have a chance to reach the upper surface of your pour. Professional resin casters use compressed air, in pressure tanks to counteract those little bubbles. 70-75psi tends to crush tiny bubbles into insignificance, often making them disappear to the naked eye.

Art

[kevin]

wehat brand of resin & rubber are you using?

[Hawk312]

Thanks for all the advice and details guys. I am using the alumilite kit, both their resin and casting silicone. I would like to try having them plated after a coat of lacquer, but is that even possible? They are perfectly smooth after some primer.

Thanks again.

[BirdWatcher]

I just bought some Westleys the other day at Auto Zone. Must be old stock. You might be able to find it online. I wonder if Black Magic is the same formula as Westley's. Anyone try Black Magic blech wite yet?

[Ben]

Soak your parts in Westly's if you can, then wash them in warm soapy water. then, after they are dry, dip the parts in Future (Pledge) floor polish to put an acrylic barrier coat on them, set them on a paper towel to wic away the excess Future. Then, after they are dry, mount them and try again.

Edited January 6, 2015 by Ben

[DrGlueblob]

Amazon sells Bleche-Wite, now under the Black Magic brand.

[Hawk312]

Thanks guys. I have heard the new "Black Magic" version of the Bleche White is not nearly as strong....very watered down or a new formula which is why I was hesitant to give it a try. Do any of you have experience with the new Black Magic stuff?

Soak your parts in Westly's if you can, then wash them in warm soapy water. then, after they are dry, dip the parts in Future (Pledge) floor polish to put an acrylic barrier coat on them, set them on a paper towel to wic away the excess Future. Then, after they are dry, mount them and try again.

Man, so many uses for Future. It might be tricky wic`ing them, seeing as how the wheels have places where it can pool up. Maybe I will just try turning them upside down. Interesting idea though. Do you have any experience having the parts chromed after doing this?