I had a part that had several layers of high temp release carnuba wax on it and when I went to coat it with PVA, it would not want to keep a thin film. The pva would act as if it was repelled by the surface.
Water and wax naturally want to repell but this hasn’t happened to me before, what could the problem be? do I need to do mre buffing?
anyone ever encounter this problem?
Thanks
two things,
buff the wax completley. You dont want to see it :eek: ha
spray a very very light coat first, like DUST it on, let the alcohal evaporate, then spray your second coat a little bit heavier, not too just enough to have a gloss, then do another coat to give a smoother finish
I thought that I had all the wax buffed off, but I guess not, I was doing it by hand not machine…
i dont know why you guys are using Wax + PVA? just use pva. it will NEVER stick to ANNYTHINGGG
normally what i do is, high wet sand my plug to 2k grit and buff. it will look like a mirror! then you spray pva, it will act up ALSO!
i have posted this over and over, the BEST way i have ever spray pva is with the small mini hvlp gun from harbor freight. its 40? $'s much more then the cheaper bigger ones. but the small one does the job. its the best tip + size for the whole operation. easy to clean and remember to clean it well!.
first, get a part that is NOT flat, something that has a steep angle to test out the settings in the gun. buff a small part on the test part thats on a angle. the reason for this is so you can test the settings, if its tooooo much then your going to spray a lot of pva then it runs (thats a no no!) if you spray to much air, thats a no no! you need it JUST right.
spray the pva on the part, 1 layer, which to me is 2 passes… 6-8 inchs away from part. let it dry for 10 mins. DO NOT apply heat or BREATH! you’ll end up spitting on it =) (trust me ive done it)
then if you have the settings right, spray some more! if its not and it runs, wipe it off with water and do it again with new settings. then , when u DO get the right setting MARK IT!!! =) so when u clean the gun u can set it back.
then. spray some more layers for testing, i apply almost 4-6 layer depending on the part.
when i demold, the inside of the mold is so shinny! no buffing needed ( i also use epoxy surface coat so no need to buff)
sometimes becareful, IF you spray toooo far from the part, you will get a grainy feel. ive had this and just sand and buff the inside of the mold when demolded.
well i hope these few tips help you guys. it took me awhile to get pva sprayed on correctly . miagi sun, wax on wax off… no wait, PVA on, pva off… lol
I found out the hard way that PVA will stick to certain materials. Its been a long time since I made that mistake.
One material is MDM, even when sealed, PVA binds to it. The other material is Polystyrene.
It was SOOOO much fun chiseling the MDM away from our casted piece. Almost wasted a couple hundred dollars of MDM, and another couple hundred dollars in casting material. Plus that mistake put me and my co-workers into overtime. I thought I was going to be fired, seriously. And it wasnt so much that I didnt wax the mold, and more so that I forgot.
I will keep that in mind, and experiment a bit…thanks.