finished up. This is a really big hood for a car and the thing weight a ton, but should last. For those that are interested, its for an older Saab. The original hood weighs about 65 lbs and with a pure carbon structure I hope to cut that in half if not third.
good job>>> 
polyester tooling gel?
did you take the mold off a hood that had paint on?
I heard that you can;t mold onto sertain paints,acrylic??/
Thanks… Yes, it is poly tooling gel. Sometimes orange, sometimes black. No problems straight over paint for me.
how thick are you laying the tooling gel 20 30mills?
that must have taken a couple of gallans…
Hay I am using the orange right know, You ever have the tooling gel wrinkle on you? I think that i sprayed to thick of coats to close together, witch caused the gel to peel away???
you could glass a couple of layers after the gel was set then pour foam, glass again to make a light weight, strong mold/.
you use pour foam. How do you get any consistent thickness with it?
you could glass a couple of layers after the gel was set then pour foam, glass again to make a light weight, strong mold/.
You’d be better off using cardboard (slices can be cut into it to fold and shape to the mold contours) but angle cut the edges and totally glass over to seal it in.
Evan was showing me the other week a PUR nd epoxy paste to putty over the mold to add thickness and keep it light in weight.
Jim, can you call me or can I call you to discuss this. you lost me on this explanation.
Just use cardboard to build up thickness and strength to your molds but keep the weight and material costs down. but the edges needs to be bevel to get the glass to lay down and not leave air pockets in the back side of your mold. You still have to use the tooling gel coats, surfacing veil and a few layers of colth before the cardboard but it saves materials and weight moving them around.
Or was it about the PUR paste?
Hey Jim,
Even show me some of the tooling dough also and we built up a door mold using the stuff. It is from PTM&W and is called RTC???. I think it is on the specialty section. It is an epoxy based putty that has a yellow and blue part that are mixed 1:1 to make a green dough. We were able to put down two layers glass, dough, and two more layers and the mold was super strong. We put the dough down at about 1/4 inch or a little more.
For the poly mold above, I put down about 25 mils of tooling get, let that set up till it was firm to the touch (1.5 hours given the shop temp/humidity). I put the gel down with a gel coat gun. I would not recommend trying to brush something this big. If the gel coat gets too thick it can blister. Also, watch your catalyst level and build the layers slowly. Once the gel coat was stable, I put down two layers of surface veil to stabilize the gel coat. I then let this cure out, then two layers chopped strand mat, cure, two more, cure, then poured the 8lb foam over the entire surface while still soupy which self levels. Let the foam cure, then two more layers. Then made large X brace with foam and beveled edges and covered with three layers. Done. The thing still weighs a ton but there is no flex in this mold and should be good for several hoods.
I have been using tooling foam made of a 2 part epoxy (yellow and blue) for years on epoxy tools. It is great stuff. before that we used a product called monkey dough. it was made by blehm plastics in Detroit. I used that way back in the early 70’s. It was great for adding thickness quickly and for eliminating man hours on the tool
The mixture that PTM $ W uses is to the best of my knowledge a formula that originated at AD Tech in Charlotte michigan. It was sold for years and we used a huge dough mixer
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=57090&item=3870756016&rd=1#ebayphotohosting
This made for quick mixing and it took a little time to clean, but it was worth it if you had big jobs.
There is also a cement mixer that works well.
http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=6970&productId=396422&R=396422
I just talked with Tina @ BJB (www.bjbenterprises.com) in Tustin Calif. (714) 734-8450 and they have a simular product too. They do have some new WC casting PUR and other items too…
JM from GGROP
JM I am going to have to give them a call and ask for a sample of the WC pur. I have a lense project that could use a good WC pur.
if you use cardboard do you just use plain or corrogated? does it need fully wetting out? im using 1mm coremat with excellent results,i may just get more of that in a thicker size 
Evan also gave me a sample of some similar looking stuff from Aptek Labs (http://www.apteklabs.com/index.htm) #6527-B that mixes 3:1. Have not tried it.
You use it like honeycomb, just bond it to the mold, let it B stage, bevel the edges and finish wrapping it to seal in the cardboard. This is for Molds and not parts. For parts, I agree with you on using coremat…
I’m not sure how available this is elsewhere …but I’ve been reinforcing the backs of my molds with a semi-stiff sheet foam board that is green and 1/4 " thick and is used generally for insulation between housing vinyl siding. Its stable with Epoxy ,I don’t know if it is with Poly or Vinyl.
Makes great strength and weighs nothing.Stiff as a board once covered with reinforcement cloths.
It can be Kerfed with a knife and then easily beveled on edge (so glass wetted will climb up and over well) I do weight it down until the Epoxy has become firm and it holds its shape.
Its not ANY replacement however for the maleable putty 2-part Epoxy dough since it can’t conform to compound curves or shapes as well. Its more for long barely arched surfaces or fields.
Cheap too ! :wink: