Bach-RCU

I have made 3 molds, but I have always used wax (Partall 2 x and Dolphin 1x) + PVA to pull the molds off the PLUG.

Then I used the PVA for the first 2-3 parts and then I just used the Dolphin wax.

I want to try DOLPHIN WAX only for the MOLD MAKING -- anyone did it ?

Bach

TT2

My Feedback: (13)

I PVA on plugs now. I don't risk the 'wax only' technique since I've had parts stick. If your PVA spraying technique is good all you have to do to get your molds ready for polishing is a quick wetsanding starting at 1500 grit (maybe 1000 if your PVA surface isn't very good) then 2000 grit. Doesn't take long, and you don't risk sticking the mold to your expensive (time is money) plug.

Just curious...why are you using Partall if you have Dolphin wax?

-Tom

Bach-RCU

that was just historical - I had Partall before DOLPHIN -- but what a pain in the ...

I now use only Dolphin,

but my reason for using wax only is exactly that I have been unable to achieve nice PVA surface -- it ends up always worse then the polished plug surface underneath

Bach

davidfee

I have had bad luck using dolphin wax over lacquer (it seems to soften the lacquer ever so slightly). Over an epoxy mold surface, however, dolphin wax alone seems totally suficient. I have had no troubles using dolphin wax only (no PVA) when making parts in my molds. The trouble is only when making the mold from the plug... you need to use a catalyzed paint, or have an epoxy surface on the plug.

-David

TT2

My Feedback: (13)

David: the carrier in Dolphin wax is kerosene...like 35% of the total composition. That's what Harold told me. I like the stuff but you have to be careful about buffing it too hard...moreso than Partall.

I might give Partall another shot because it builds up gloss faster than Dolphin wax. I'd only use it on plugs though due to the difficulties in applying. Last time I used it I kept getting too much on, then it was tough to remove. My tub of the wax was about 10 years old and VERY stiff so I'm sure that contributed to my troubles.

Do you JUST use Dolphin wax on the first pulls from the mold?


Bach: It's impossible for me to get the kind of finish with PVA that I can with PPG urethane paint, but I can get pretty close if I'm having a good day. Here's what I do:

1. Spray on a dust coat with an HPLV gun (The gun I use is an Astro Pneumatics Mini with an 0.8mm tip). The needle should only be 1 1/4 turns out for the dust coat. You should just barely see the mist coming out of the gun! When you spray it you have to look really close to see any on the surface. You want as small droplet size as possible with decent coverage.
2. Wait ten or fifteen minutes.
3. Open the needle on the gun 2 turns (3 1/4 turns out total) and spray a flow coat. The surface will look pinholey...don't sweat it...after a few minutes all the PVA will flow together and level out leaving a nice gloss. If it flows together completely immediately after spraying then you have sprayed too much on.
4. Wait 45 minutes.
5. Spray another flow coat on
6. Wait 45 minutes. Done.

IMO, the finish quality that the PVA gives is OK for molds for parts that will be post-finished, but not good enough for carbon fiber parts unless they're getting clearcoated. Parts / molds release sooooo easy with the PVA that they don't even 'POP!'...they just kinda slide apart. Saves a bit of sanding and polishing time too...I only wetsand the plugs down to 600 grit...the PVA does the rest. The finish seems to be better when it's used in warmer temperatures (like 80 degrees).

If you blow it and end up with orange peel or some other nastiness (like accidentally sneezing on a perfectly PVA'd surface...been there, done that) just take it off with warm water, dry it, give it a wipe with your wax polishing cloth and hit it again. The stuff is cheap.

The only waxes I've found that work well with PVA are Partall and Dolphin wax. Neither Meguiar's #8 nor Mirror Glaze carnauba wax work...the PVA fisheyes badly when spraying on the flow coat.

I cussed PVA until I found out the proper application procedure. My success with it is due to what others have said here before. THANKS BRUCE!

-Tom

daven

My Feedback: (1)

Tom,

I apply PVA pretty similar to how you are doing it, although I don't ever try to do a flow coat. I just use 3-4 VERY fine mist coats seperated by about 15 minutes each. My only issue with PVA is that you cannot mask in the molds for painting. I've pulled 6 wings out of my molds, the first 5 with PVA, the last without. It stuck a little more than when using PVA, but did not damage the molds. I use dolphin wax also, much easier to apply than partall.

davidfee

Tom,
Good points, and a good question about first pulls. I admit that I sometimes still use PVA for the first pull, but I have skipped it once or twice on small molds without problems, also. A key is probably the age of the mold. If it's a brand new mold, say less than a week old, which hasn't been post cured, I'd bet there's a strong chance that the surface is still somewhat reactive and will be more prone to "sticking."

But I really agree with you about using PVA to protect your expensive plug.

-David

Bach-RCU

So anyway, I used only Dolphin wax 10 applications on small electric airplane plug ( ww2 fighter) and it worked perfect. The plug had fiberglass polished surface, the tooling layer was the Fiberglast tooling thick epoxy, the openning was uneventful, the surface is great.

I guess it might be an alternative, albeit little riskier for those who have tough time with PVA application.

Bach

goony

PESONALLY I dont use PVA BUT you must bare in mind I do this stuff for a living!!
SO I HARDLY ever do a 1OFF and even then I dont use pva in case in the future its needed again SO all my molds are perfect and very tough and to get these results needs a lot of work SO u need to decide HOW much work you are willing to put in!!
and also how many parts you are going to make if its only a few then go down the pva route but if you intend to make more than 10 parts then its worth the effort to do it properly

goony