A PVA Mess!

THINK A LITTLE !!
What would cause cob webbing ??
maybe the PVA is to thick and drying in the air before it has time to reach the mould !!
right ??
so what you going to do ??
work faster ?
get closer ?
or simply slow down the reaction ??
what will slow the reacton !!
water !!!
Its a microscopic film of pva you are after !! like a skin of cling wrap to be the release barrier between mould and product . Need i say more !:?:

 

Hi Tunnels,
I agree, the most likely reason for cob webbing is the material being sprayed is drying in the air before it contacts the surface. I'm no expert but it seems to me that you have several options when this happens. Increase your fluid flow setting, decrease the air pressure, switch from a siphon to a gravity feed, or thin your material. Your course of action is going to depend on what you're spraying and what equipment you have or can afford.

Just let me say that I'm not disagreeing with you, or disputing the fact that your method of applying PVA works because it obviously does. Like so many aspects of fiberglass boat construction and repair there's almost always more then one way to skin a cat, and I guess in the end what matters most is the job gets done right. Now how each individual decides to get there and what logic he uses to determine his course is going to be almost as numerous as there are people involved in the process.

The reason I joined this forum is that even after 30 years of working with fiberglass I know there's a lot I don't know. It didn't take me long reading through a few post on here to realize that the guys that frequent this forum are experienced, knowledgeable, friendly, and exceeding helpful when it comes to helping others. Your posts on PVA application perfectly illustrate that point. This is something you learned over the years, used to good affect, and now you're passing on that knowledge.

My experience and outlook may be different then yours but hopefully my point of view can and will provide the reader an equally viable option or opinion. At the same time I'm as ready, willing, and able to learn something new as the guy that just bought a pint of resin and a yard of cloth thinking he was well on his way to a new boat.

To be perfectly honest I might try your application myself just to see how it looks...I've got three air intake molds out in the shop that I'm working on so the opportunity is there. At the same time there's a part of me that would resist telling anyone that it's perfectly acceptable to leave your mold unwaxed, and spray on a heavily diluted, invisible layer of PVA as your only release agent. It doesn't matter how many times you might have pulled it off in your career..their skill level may not be up to the task...and that worries me.

The risks are so high that something might go wrong and a part fail to release that I would feel awful if that happened. Because all of my plugs and molds are basically one off custom parts they'll almost certainly never have the chance to become seasoned over five or ten pulls, so I take extra care to make sure the first pull works every time. Usually that means several coats of wax, a spray on release, and PVA.

I'm not saying it won't work only that this procedure should be intended for experienced users who know and understand the risks involved.

Mike

 

Yeah working with one offs is a little unnerving . The pva thing has always worked everytime so i dont think about using anything else . When i was in Korea we were stretched to the limit for months and could not afford one single mistake so i used pva all the time . One flange they made in the other factory got waxed 10 times and the gel coat was brushed on !you guessed it was the only one that stuck and boy did it stick !! The TR wax they were using and had never used before was not compatable with the gell coat that was manufactured in Korea . So i went and collected everytime and put them in a box and taped it shut and hid it so no one cold find or try to use it . The wax they were using themselves was Johnstons floor wax !! its in every country i ever been !! They had never had any problems . The TR was ok if the gel coat was sprayed !! if the gelcoat was brushed !disaster in a bug way !!. BUT the pva was the barrier that shielded the two from each other in out case . Before i left there i showed and made sure the old painter guy knew all about it plus lots a other things they had had difficulties with as well . Learning from other and handing on ideas that work is what my life in glass has been in recent years ! My first trip outside of New Zealand was a reall eye opener . i was younger and cocky as hell and knew it all !! or so i thougtht. wow the first week i found i knew next to nothing and felt a reall fool . but gradually i was able to add to what the guys knew and we had a really good time . What works in one place most times wont work some where else so its the aqumilation of knowledge and know how i have that i am able to adapt and show others . FRom the tropics and plus 40 c to china and KOREA and minus 20c and everything inbetween the greatest thing is you never have to speak one single word just hands on always . show and dont say a thing !!.
I could never write all that i know and theres hundreds of peole just like me . Its all handed on from one person to the next and so it goes . When things dont work how they should go back to the begining and absolute basics and start a fresh !!. Complicated has to many things that can and will and do go wrong !!

 

stick ups !! not all wax's are not compatable !!

Not all products are compatable world wide so you have to take lots a care and do some exsprementing of your own .
What works in one country does not nessasarily mean it will work some where else .
From the pictures you will see the brush strokes where the gel coat has disolved and eaten through 10 coats of wax and had mixed with the gel coat !!!
I hear signs of disbelief . they were brand new brushs straight out of the box

SPRAYING THE same gelcoat this never happened !! its not just in one place its the whole complete length of the flange moulds ,both of them ,more than 72 feet in total ,
The more it was brushed the worse it was Dip into the gel coat and apply with just a couple of strokes was reasonable but the more it was brushed the worse it was !!

Later when we had more time we did a test sample to confirm what had happened and yes brushing was a no no ! ,spray was ok !just !!.we had always waxed everything but as a further safe guard i had pva'ed as well

This was TR WAX !!!!

 

Hi Tunnels,
I agree wholeheartedly with you!

Since I'm usually working with "quick" one offs I know that my biggest problem is I'm not taking the time to insure that perfect finish, I'm just trying to get the part made and out the door. I know for a fact it's this hurry up atitude that tends to get me in trouble, and even now leads to screw-ups on my part. The two gooseneck air intake molds I just pulled from their plugs are a good example of what can go wrong. I was working late the other night and decided to go ahead and spray up the gel coat...which I did. By the next morning when I should have been skinning them out something came up and it didn't get done. When I finally did do the skinout the gel coat pulled and now I have to spend even more time reworking the molds.

For me right here, right now, with the material I'm using if I don't get a skin on at just the right time (usually 3 or 4 hours after spraying) there's a pretty good chance my gel coat will be less then agreeable...lol. Now I've seen guys recommend spraying one day and skinning the next, but it just never works for me....ever!

Your wax story and flange pics remind me of my first mold I ever made (30 years ago). I waxed that thing for days, buffing and polishing my little boat mold every chance I got. I never did get that thing apart to see what it looked like inside...I guess it didn't matter too much after I drove my screwdriver through it once or twice.

On the other hand I've seen one coat of Johnsons floor wax part like it was made out of butter...too bad they don't sell it in the stores here any more...I loved that stuff.

What I do know that is that everyone's experience is going to be a little different based on their particular situation. What works for me today may not be the best possible solution for another guy, because there are just too many variables involved. All we can do is give them our advice and opinion's and let them sort out the rest.

Mike

 

I just did this and I am so happy with the result. I had to rip off the gel and first laminate because I spilt resin and ruined the job but the laminate and gelocoat came off so easy.

Anyway, I have to go do the gelcoat again so I am going to make a video for you all to demonstrate what is explained below.

My plug is 8m2 surface area.

Thanks so much for this information. It really is the secret.

 

well what do you think ?

So it worked ok !!!
Its easy , its worked for me everytime since 1985 when i learned and now another agrees . its not fool proof but its pretty close to it !

Brazil !! now thats a place dont hear much news from !! What kind of things you making ??

Take care !!

 

I agree with the spraying of the pva, I seem to remember adding a splash of metho to speed up the drying.
For small jobs a piece of sponge is better than a rag.
Fish eyes are caused by not allowing the wax to dry off properly or not polishing it off properly.
I always used 2 rags a remover and a polisher, chuck the remover when the polisher starts to load up and get a fresh polisher.
Not all pva is equal either, the coloured stuff we used to get was crap, the clear stuff is way more betterer !
My 2c.

 

They have stocked out of gelcoat here in this state of Brasil Florianopolis.
So I dont want to spray up the PVA again yet for my next try. But I will get my Iphone and make a video for you.

The PVA hits the surface it is 99% dry already. You can't touch the surface as was explained by Tunnels, - well you can if you dry your hand and don't stop yoru hand but I wouldn't recommend it because if your hand puts moisture on the surface which will cut through the PVA I promise you that is going to be the place where you will see lock up.

DOn't touch it. It is there. Trust science. It is there.

Its dry immediately because it was so thin in the first place. I added 50% water too. The surface never saw wet. I couldn't believe it. Amazing. Tunnels should not have told anyone this secret but alas now everybody knows. F the Mold Release. They can all go bankrupt. PVA all the way!

 

*You might as well put Mold Release wax on your plug for the first time and as a back-up for in case you drip sweat on your PVA. But you won't bother using wax much ever again after you have become familiar with this secret Tunnels kindly shared with everyone.

 

I allowed my wax to dry for a good two hours in hot weather and like you say also I used two rags - First rag to cut it all off and the second rag to polish it while blowing air over it to remove all the dust ready for the next wax or PVA.

But I don't see how you can get fish eyes if you do the PVA the way explained in this thread. If you can see it you have too much coming out. Its more like a mist process. If I put the gun in front of my hand for example, about 500mm away, my hand starts to get sticky after about 10 seconds. But I can't see anything coming out of the gun. I can see right at the nozzle I can see but nowhere else.

Tunnels, you never mentioned how long it takes you? It took me 30-40 minutes to empty a 500ml cup through the gun. And I have a 100psi compressor and a 1.2mm gun.
It would be great to see a video of you doing it. I will go make a video of me doing it.

But Tunnels, 40 minutes is a long time. I want to be producing 10 Kombi poptops per day. If I am going to cause a hippy revolution in Brasil man, you know, I need faster method. How long does it take you?

 

I am making a Kombi poptop mate! hahahahahah.
They have 1 million Kombis here and not one poptop! So I reeingeered everyting in Inventor and I got to do everything myself cause you can't pay anyone to work for you here! hahahaha. Kombi poptop!
Here she is with flange in the plug - https://www.youtube.com/watch?v=wSMZy7aVsko

 

Complaint about PVA -
https://www.youtube.com/watch?v=K3D1GYQWYCg

Is this sludge from the PVA or from the 12 layers of that TR Industries Carnauba mold-release Amazona Women Wax Release crap which also takes an hour to put on and take off?

I have to nail this process. I need capacity for 24 per day closed mold. RTM.

 

aaah Brasil !!!

To produce so many every day from a single mould is one every hour ! resin and gell and glass impossible !!
So make lots moulds all from a single plug . wax your moulds first then use the pva spray is instant dry so gel coat straight after ,before gel coat is dry but has gel then you gently start to lay the glass and gel coat mixed with the resin so you get better colour deepth is into first skin of glass then finish glassing !!
If you are single person process then after two days you can sleep maybe !!
With 4 to 6 moulds it could be a completely on going process one after the other . when the last one is finished would be time to release and re-gel the first one then a second and round and round .
Use the sun to cure the finished product .
Shrinkage and distortion and all the bad thinks that go with trying to do the impossible !! but i will say you will learn more about what you can do with the materials and there capabilitys you have on hand !!stretching it to its limits ! and knowing where those limits are !! now thats what a lot of people neve get to know so never understand what is possible !!

Pant hose or womens stockings !!, two layers are best to use as a strainer for the pva !! just pva and water mix in a container and let sit for a time then strain into the gun pot ,and yes not all pva's are the same so get familiar with the products you have and know what works best for you and stick to that system , I have heard of guys using some metholated spirits but have never had any cause to want to try it !!.

 

RTM Closed Mold?
http://www.youtube.com/watch?v=MWUxhC6-q0c
That mold looks like it can do 1 per hour?

How long does it take you to spray out half a cup (250ml) of PVA with the method you describe above? It took me about 20-30 minutes.