New Mold Release agent

I should have said "it was discovered in the early days of composite". And it was during that time that salesperson were still harping on the superiority of silicon based mold release and multi release agent, not knowing that it is common knowledge amongst composite manufacturers to steer clear of silicon based release agent. One was even claiming that the "cured" silicon rubber mold does not exhibit silicon migration on the ground that it is cured. Rubber mold was used as a caul plate for parts that require well defined corners or relatively flat surfaces.

Not until this "new" product shows a report that it does not exhibit silicon migration, I will be wary.

We were just careful then (even now). After all we were making aircraft composite parts and the quality control in place was very strict.

 

I would not get to excited just yet !!

Had a look up on there website and did some reading so check it out first
http://www.chemtrend.com/application/composite_molding/semi_permanent_release_systems
:?:

 

Here's more on mold release covering several brands. Note that "There is no universal best mold release," and they make distinction on silicon based product.

PVA or Partall is still the best insurance for contaminated/uncured/unbroken in mold.

http://www.compositesworld.com/articles/mold-release-update

 

Thanks for the history.
I have contacted the manufacturer stating the silicone concerns. I will post the reply.
Fred

 

Report on Chemlease

I did talk to their company rep about silicone in the product. He said that in the early days silicone migration to the part was a problem. Chemlease has the silicone suspended in a resin that once cured to the mold surface has absolutely no transfer to the parts being made. He is aware of the rumours floating around about silicone contamination. With this product it is not so.
I am relieved to get this information. It works so well.
Fred

 

I stand corrected!

I tried spraying a coat of clear coat into the prepared mold and it would not lay down. It fished eyed so bad that it looked like peas cut in half and stuck all over the place. I checked my equipment and sprayed another mold with a wax and PVA release and it layed down perfectly.
So it looks like silicon is on the surface. I haven't tried painting a part that has come out of the mold yet but don't have much hope for that working out.
I will post further test.
Fred

 

You have what is probably an over slippery mold, typical of silicon waxes. A mold release rep once showed me the trick. Try sticking a piece of masking tape over the mold surface. If it won't stick, your mold is too slippery.

No, the silicon migration has not started yet. It takes a long time.

 

Gel coating over a silicone surface wax !

You not thinking !!yes you have a slippery mould and if you want to get your gel to stay have to spray it in very fine coats one light fine spray and wait for 5 to 10 minutes for the thixo in the gel to settle and hold then another fine coat and wait again !!! always fine spray as fine as you can get and keep your air pressure down!!, fine spray and wait !! fine spray and wait !! by the time you get to the thickness you need your with your final spray the first coat will have or should have gel-ed and so you are doing wet on semi wet spray is what you are trying to achieve .
One single fine coat of PVA and very dry SHOULD SOLVE THE PROBLEM as it will hold the gel and is the barrier coat between the wax surface and the gel coat but remember fine spray and wait !! fine spray and wait !!
In tahiti we used silicone car wax as its all that was availible . The tahitain guys were absolute experts at gel coating over silicone without using pva !! IS IT something new ? not at all i was there 1984/85 and they had been doing it for ages .
There is really nothing new just resirected old ideas that us oldies used long time ago and the newbies have seen before !!

 

automotive and fibreglass products are usually two differant systems !.
Personally i would not use something on a mould unless i did some testing on a old mould first and not just once but at least 3 to 4 times . if you have a system that works and you know it works well why change it !! play the safe bet and do what ever you done before .

 

Many of my customers use Chemlease products and I know the rep for the West Coast and distributor very well. All types of parts are made with it, even large truck and RV parts that are sanded and painted. There normally isn't an issues with fisheyes or beading up as you described when gel coat is applied unless the wrong product was used (there are many versions and you need to test to find the right product for your needs), or there was an issue with the application. Over application can be a problem, typically you only apply a very small amount to the surface and then spread it thinly and evenly.

Which one of their products is it you are trying to use?

 

Well Tunnels your technic worked out great. I tried spraying automotive clear coat in the Chemtrend released mold again the way you described spraying PVA. It took longer and to my amazement it layed down a very nice shiney perfect coat. I waited for it to cure and then Vacuum infused the carbon fiber with epoxy. The part came out spectacular . To check for possible silicone I wetsanded and sprayed clear on the part. It came out great. So I really like this Chemtrend product after all. I guess the problem I was having was the viscosity of the clear was to thick even atomized to lay down on such a slick surface. When sprayed like a fog it would stick.
Thanks
Fred

 

Best news this week !

wow thats the best news i had this week !!
Thanks for the feed back !
Like i said where ever you go you pick up little things i am glad to have passed it on !!

Thank you and take care !!

 

hi.
do you have standards or guiding about composite secondary bonding such as "better time to assembly of two pieces after curing them whit lay-up model(out-time) or roughness of surface or surface treatment?
my issue is tee connection whit epoxy adhesive
if anybody have,please send to my mail.
very very very thanks
v.azimzadeh.68@gmail.com

 

I think you are asking how to bond two pieces that have already cured.
Well the best way is to have used peel ply against your carbon lets say. When cured you peel it off and it leaves the bestbonding surface there is. If you didn't use peel ply you will have to rough up the surface before you bond. It doesn't matter how long you wait before you bond with epoxy composites.

Hope this helps.
Fred

 

In the case of using peel ply its is still a better option to 16 grit grind the surface and get into the glass fibres . 0ther wise it purely a chemical bond and not a physical bond as well !!! if there any gel coat it also needs to go right to the bare glass surface .