hi .. new member .. wax and first mold questions

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#1

hi … my names’ Leroy in tennessee … i’ve been an autobody and paint guy 10 years … but am moving into producing my own composite parts instead of taking collision work … i’m familiar with fiberglass and have repaired countless dually fairings and trim pieces … but have never made a mold … i am starting with a cutom grille and have the plugs made .

here’s my dilemma … i have been collecting everything i need to make my first molds … and researching how to make the mold … i think i have a good idea … i have been designing plugs for 4 months and they are complete less final wet sanding and buffing out with wax…

i have partall 10pva … orange tooling gelcoat … glass mat … rollers … acetone … all ready … but i was unable to locally source a 2lb tub of partall wax :confused:

my main concern being a auto body painter for 10 years is obviously fish eye prevention and paint adhesion after demoulding the pieces … i know well enough the dangers of silicone and it’s scurge on all things paint …

i would really prefer to use the correct wax with the pva … but can i substitute another wax for making my molds and parts … or will this create a problem ?

i would like to spray the pva if it will lay down in the mold well without running … most are 4 inches deep … narrow and with angles … i am guessing it’s somewhat like urethane clear coat in how it lays down … correct me if i’m wrong … also i read here in these forums that a corner of a t shirt rag wiped works well too … so if the sprayer i got dont do it … that’s the plan B …

so i was thinking … based on the suggestions i read in a previous thread … that using either mothers California gold ‘pure’ carnuba wax … or meguires carnuba wax … might work … does anyone have experience with these ? can i spray down the pva over either of them without it beading up … and is there any more desireable atributes that i should choose one over the other … or is there something better i can use available locally at a parts store … or should i keep trying to nail down partall wax#2

also when i go to layout my plug molds the feller i got most of my materials from was suggesting how i build the mold … he said to make a thin bead of play dough and make a radius around the top (bottom) edge so the mold has a taper not a straight 90 … is this correct … about how steep of an angle should i make this radius ? 1/8 inch … 1/4 inch ? should it start at the bottom of my plugs or at the top of the side of em ? any advice on how to construct the mold is appreciated … he suggested 3 layer … 4.5 in 1 1/2 mat which should be about a 1/8 inch mold … which seems kinda thin to me … but is that appropriate ? said because the intracacies of the contours it would release easier not being too thick … but i also would like it to last awhile … what do you think?

also he suggested using wax paper under the mold … is this a wax paper layer on top of the play dough or can i smear wax and then pva the playdough and build right on top of it ? is there a better way to make the edges and how should i layer the PD / wax paper ?

should i cut the mat to my paper paterns before hand and how much should the strand mat overlap on the first layer if at all ? someone online suggested in a previous thread not to overlap the edges of mat on the first layer because heat will cause distortion … but at the supply warehouse the mold maker said it’s not a problem … overlap with mat is okay on a small part he said so that’s a conflict of advice … but i tend to go with what an expert says over an old internet article …what say you ?

i think i will be paintbrushing the tooling gelcoat … should i just apply 1 thick … even layer … or 2?

also i didn’t get any literature with the orange tooling gelcoat … does anyone know how many drops of mekp this should get per ounce?

i have bondo resin but he also gave me a mistery tub of resin … i can’t find any information about it online even on the manufactures website… if anyone knows about this please let me know … i will tell you what the label says … polynt composites 970g353c-qm pirogue green material# 924071 ((contains: diethylene glycol, titanium dioxide) i can’t imagine it’s just those 2 ingredients … but for what it means thats what it says?) i got it from advanced plastics …

They were very helpfull and had everything i needed … Though they don’t sell the tooling gelcoat or resin in small batches they were kind enough to give me a small amount of each as a sample … As the saying goes … You don’t look a gift horse in the mouth … So … I didn’t even look to check for any literature and there’s nothing to go by except what’ labels on the resin tub … And the tooling gelcoat is a plain can … so that’s what that’s about …

any tips / tricks are appreciated

thanks in advance for your replies and assistance …

#2

Have you tried contacting the manufacturer of partall paste #2? maybe they can send you a sample for testing?

#3

Welcome. That’s some questions you have there!

i would really prefer to use the correct wax with the pva … but can i substitute another wax for making my molds and parts … or will this create a problem ? Stick with a proven sealer/release agent. Correct paint prep will remove any issues with paint application(as you will already know)

i would like to spray the pva if it will lay down in the mold well without running … most are 4 inches deep … narrow and with angles … i am guessing it’s somewhat like urethane clear coat in how it lays down … correct me if i’m wrong … also i read here in these forums that a corner of a t shirt rag wiped works well too … so if the sprayer i got dont do it … that’s the plan B …Spraying PVA gives the best base in which to apply your gel. Another method of application is by sponge, although this usually transfers the wipe pattern on to the mould and needs rubbing out following demould.

so i was thinking … based on the suggestions i read in a previous thread … that using either mothers California gold ‘pure’ carnuba wax … or meguires carnuba wax … might work … does anyone have experience with these ? can i spray down the pva over either of them without it beading up … and is there any more desireable atributes that i should choose one over the other … or is there something better i can use available locally at a parts store … or should i keep trying to nail down partall wax#2
Never had an issue with the PVA beading on the waxes we use. Stick to composite sealers and release agents/waxes designed for that purpose.
also when i go to layout my plug molds the feller i got most of my materials from was suggesting how i build the mold … he said to make a thin bead of play dough and make a radius around the top (bottom) edge so the mold has a taper not a straight 90 … is this correct … about how steep of an angle should i make this radius ? 1/8 inch … 1/4 inch ? should it start at the bottom of my plugs or at the top of the side of em ? any advice on how to construct the mold is appreciated … he suggested 3 layer … 4.5 in 1 1/2 mat which should be about a 1/8 inch mold … which seems kinda thin to me … but is that appropriate ? said because the intracacies of the contours it would release easier not being too thick … but i also would like it to last awhile … what do you think? Always worth putting a small taper on a tool to assist with demoulding where possible. Thicknesses of tools vary from job to job. You always want to remove the moulding from the tool, i.e. the tool always wants to be thicker than the moulding. We have several small moulds with a lay-up of 1 x 300gsm CSM and 4 x 450gsm CSM giving around 5mm in thickness. Parts manufactured from these are around 2mm

also he suggested using wax paper under the mold … is this a wax paper layer on top of the play dough or can i smear wax and then pva the playdough and build right on top of it ? is there a better way to make the edges and how should i layer the PD / wax paper ?Not sure I understand the instructions given

should i cut the mat to my paper paterns before hand and how much should the strand mat overlap on the first layer if at all ? someone online suggested in a previous thread not to overlap the edges of mat on the first layer because heat will cause distortion … but at the supply warehouse the mold maker said it’s not a problem … overlap with mat is okay on a small part he said so that’s a conflict of advice … but i tend to go with what an expert says over an old internet article …what say you ?
Exotherm during the cure gives off heat. However, applying 1-2 layers will see no distortion. If you don’t want to overlap simply stagger the joins on the following layers
i think i will be paintbrushing the tooling gelcoat … should i just apply 1 thick … even layer … or 2?
I hear people say “i’ll put on a thick coat instead of 2”. Definitely the wrong approach. Always do two light applications. The manufacturers datasheet will advise optimal coat thickness. We generally do the 2 coats in different colours. This gives us a good guide as to how far we are through when the need arises to wet sand the moulds surface. Brush application is fine. I would suggest using an old brush for gel application. Its all too common to think a nice new & clean brush will be best, however new brushes will lose many bristles!

#4

thanks for the welcome … and the responses …

it’s been a little while since i posted but as i was new member i had to register and i just now sent the response and so now it posted …

i figured most of it out now …

i got johnsons paste wax from home depot …

i figured out how to spray the pva … hit up like 25 ultrafine coats so as to prevent mekp reaction with any of my plug … i sealed the edges with heavily waxed shellac though i used urethane auto paint before i knew that was a no no and that it’s best to use duratech 2k primer … so gonna have to get some of that … though i think it’s sealed well enough that the plug will no bond …

i put a nice taper on the plugs and built flanges with formica … and glued them with baking soda hardened super glue … finished with playdoh and sealed with leftover waxy shellac i had from a dewaxing operation … it looks good

i strapped the table with 2x shipping style ‘seran wrap’ and threw it away now and again …

i layered 3 laminations of csm with polyester resin … then got creative … to save time - money - and hopefully make a more durable mold i made a foam form and backfilled it with a blend of resin - bondo - spare glass … i don’t know if this is a good idea … but it’s done now … i haven’t pulled a plug yet … just finished the first mold earlier tonight …

i am going to see how well it releases … and if it’s tight i will drill a hole into the rondoglass and tap an air nozzle to fit and blow the parts out …

also … as per a recomendation on this site i emailed mclube and asked to test out their release product … but i have this wax and pva for parts next week … i hope it all works out great …

i’ve been working on this now … an updated grille for older ford f-series trucks … for some 4 months i guess … though better then half my time is spent with my little boy jackson … he’s 2 1/2 … so that takes awile with him … but … he’s my big helper …

i started … and still am … working from a point of extreme ignorance … ignorance not being stupid … but unaware … i just started designing and building a plug out of common autobody materials … and didn’t realize there were so many faster … cheaper … easier methods i see now that i have looked …

gonna be awhile but i’m gonna do a whole line up of products for these older trucks … with favorable wind i will me pulling these grilles out next week … and have them painted and finished by weeks end …

glad to be with your forum and look forward to learning with all of you … thanks … leroy