I use only wax on the moulds for motorcycle tanks I make, and have found I only have to apply one further coat of wax after making several tanks.
Seems to me the main problem many people seme to have with wax is they think that the purpose of waxing is to produce a shiny surface, so buff the wax like they would a car body, which results in a good shine, but little or no wax left on the surface of the mould to allow proper release of parts…
Sorry what I mean was I know that on a fresh mold you put about 5-6 layers of wax on and then after that one or two coats on for every new part you pull off right? Well my question is that since I use hot water to depart some of my parts, would that melt or wash away all the wax? Would I need to put on a new 5-6 layers on again or just one or two?
Thx
Yep. 1 coat of wax before each layup.
And no hot water will not wash the wax away.
If you keep waxing a well aged mould for no good reason, then you will end up with lack of definition on any fine detailed areas, and possibly other associated problems This is something that is quite well covered in the Forbes Aird book (ISBN 1-55788-239-8), which also covers the proper procedure regarding preparing new moulds for first use.
After the last coat of wax is applied to a new mold, how many hours should i wait to spray pva on it and then use it? I’m hoping it’s ok to just wait 2-3 hrs after the final coat of wax is buffed?
why use pva? if you made a gelcoated mold and waxed it, there should be no need to use pva
I don’t want to chance the mold getting any epoxy resin glued to it; PVA is just extra insurance.
I think your waisting your time. just do a tape test to ensure you did a good job, or switch to a semi permenant release. I have only used pva twice in my life, I would only use pva when I have a really old mold that does not have a shiny surface or has alot of purosity. using pva on new gelcoated mold is not neccesary
At my old job we would apply wax and spray almost immediately after buffing. Never had a adverse reaction with PVA.
Im with Hojo though. PVA is a time killer. Some of your higher end parts manufacturers use teflon tape on tool surfaces. For masking and as a release agent (instead of wax).
Didn’t have to wait for the wax to out gas?
I use either wax or semi-permanent release on all molds, never use pva unless the mold is in hagard condition. if you have a mold that is in good condition and you are having problems releasing your parts due to poor waxing job/poor wax, then you really need to switch brands/technique or use a semi.
There is no need at all to wax a mould every time, and you only need to apply 3 coats initially to ensure the whole mould surface is covered.
Detailed info regarding all this can be found in the excellent Forbes Aird composites book.
I’ve never heard of this teflon tape stuff, what is it like?
it’s teflon, in sheet form. not much sticks to teflon!
It’s been over 24 hrs so i’m not worried about it now. lol I got tired yesterday after waxing and cleaning up my mess, so i called it a day. I’ll probably infuse the parts tomorrow. Man… off topic, but our temperature here in Phoenix has dropped dramatically, from constant 108F down to 93F for the high. Much better for work.
I totally hear you guys on saying PVA is a waste of time, but this mold has some fine pin holes and fine sandpaper scratch lines. I don’t feel like spending any more time repairing this mold to make it perfect.
try coating with a few layers of wax, then pva over that. I did this for a part and it literally fell out of the mold! when you do the first few passes of pva do a very light dusting allowing drying inbetween (a hair dryer is great) or else it will repell like water on an oily surface.
I’ve always been scared my self when it comes to bot using pva. Should I continue using pva on parts that have very fine detail? For example recessed lettering with sharp edges and corners? And then experiment on parts that don’t have as much detail?
If you do not need it, do not use it.
Thanks Herman. 
The other night we actualy took a mold that has embossed lettering, 90 degree 2mm high edges, and lots of pin holes. We sealed that mold twice, and then waxed it 7 times. We poured resin over it as gel coat, then put on three layers of 1.5oz matting. It peaked off like butter 8-).
I then took two live molds we are making parts out of, put 5 super thin mist coats in one, 3 on the other, and those parts popped out before we were able to pull all the peel ply off. On those two molds we also did two coats of chemlease #15 and seven coats of wax.
Btw is chemlease suposed to be coagulated? It’s not a liquid. It’s like somebody took jello and threw it through a blender. We put some on the rag, then wiped it in and all the chunks fell apart and wiped on well. I’m just thnking we picked up an old canny it wad in sale for $40/qt. And the can looked oxidised…
Unfortunately, the internet is loaded with pictures of people who tried to fabricate molds and parts with only wax and ended up with severe sticking…especially those who work only with epoxies. The chemistry of the mold/plug surface, paints used in the process, and the layup resin all play a part in the quality of the release. When a new mold is made, not all molecules within the surface coat get chemically linked. This means that there are some open reactive sites on the surface of the mold. When you put fresh resin into the mold for part fabrication the molecules in the resin can be very eager to bond with open sites on the mold surface. Wax typically cannot block this reactivity and PVA is used to create a barrier. With a polyester based surface coat the PVA actually progresses the cure of the mold surface. Overtime there are no longer any reactive sites in the mold surface and the mold is said to be “seasoned”. Wax provides slip and PVA blocks the chemical reactivity.
On some plug/master surfaces the reactivity due to the chosen paints can never be eliminated and PVA is an absolute must. Some plug surface present no potential for chemical linking and wax is sufficient.
Aggressive polishing (above fine grit) actually damages the chemically reactive sites of some resin making PVA unnecessary. I personally never polish molds. Polishing plugs is so much easier. Since I don’t polish the mold surface I may have seen more chemically reactive issues.
The key is testing the entire process forward and backward before you commit to fabricating a mold or part with a chosen release system, plug surface, mold surface, and layup resin. Change any one and wax alone may not work. Change any one and some semi-permanent release systems will not work. I know of some epoxy resins that will not work with Frekote FMS/770-nc.
TEST! TEST! TEST!
I’ve seen enough failures to know that wax alone, without PVA, doesn’t work with every combination and process. In my opinion if someone recommends a release product/process they need to be very clear about the release surface and the layup resin.
Applying Wax & PVA
I allow 15 minutes between each coat of wax and about 1 hour after the last coat on new surfaces. I only apply 4 coats on a new surface. With Part-all Paste #2 I buff immediately after application. With Mequiar’s #8 I wait about 10 minutes before buffing. I’ve seen some people wait too long and then have to work really hard to buff. This can lead to over buffing. I prefer to start buffing too early rather than too late. I use two buff cloths. One to remove the skim/excess and one to buff to gloss.
The only wax that I know of that doesn’t cause the PVA to bead up is Rexco Part-all Paste #2. In a production scenario I wax and spray within 10 minutes. In one application I waxed once every 10 cycles put used PVA on every application. I personally would rather spray than wax and buff. Spraying PVA onto Meguiar’s requires multiple light mist coats prior to a flowing coat to prevent beading/fisheyes.
I use semis almost exclusively now. I typically do more complex parts so I’ve been able to get more than 3 cycles before needing to reapply. With some processes I need to apply a fresh application before each cycle. This still saves me time and releases are so beautiful.