I am new here, so I would like to begin by adding something useful.

[Sean Matthews]

I am a mechanic by trade, and I have been working closely with a Fibreglass specialist who have recently built a Fibreglass bonnet mould from scratch, whilst documenting the process along the way.

Although this is for a 1965 Dodge Dart, hopefully you can appreciate the method rather than the make and model

I thought it was such a useful article, it prompted me to share it on here. This forum doesn't let me posts all of it, so I will put the contents up and you can read the full article here.

Hope someone finds this useful and helps!

Contents

How to make a Fibreglass Mould - Working with Formex Fibreglass

• What you will need
• Equipment and fibreglass tools you will need for the mould making process
• Inspect the pattern
• Preparing the pattern
• How to apply a gel coat
• Laminating the first layer of chopped strand matting
• Finishing the main laminate
• Adding reinforcement (optional)
• Removing the mould
• Trim and finish
• Conclusion
  
  Thanks for reading!
  

 

[Randy V]

Great introduction Sean! Flat panels are not easy to make either!
I take it you have an interest in the GT cars?
Welcome to GT40s!

 

[Brian Kissel]

Welcome to GT40S Sean. I’ll check your article out as I get a chance. Enjoy the forum.

Regards Brian

 

[Michel]

Read this article ; all basics are welll reminded but .......;
There is something strange writed on the gelcoat procees to do ;

• Once cured, sand down the surface and remove any imperfections ready to lay up the first layer of fibreglass.

In any case don't do that!!!!!!! gelcoat need to cure and stay tacky and then you start laminating
It's strange to read this phrase because below you can read read another expalanation ????? so probably some wrinting mistake ????
But have to be corrected because people doing that sand onto the gel will destroy all the work and maybe damage the mold or the plug !!!!

Jusst my 2 cents

 

[Sean Matthews]

Great introduction Sean! Flat panels are not easy to make either!
I take it you have an interest in the GT cars?
Welcome to GT40s!

Thanks Randy, yes of course, proud to say I got to work on a GT40 a few years ago, and loved them since. Never been able to afford one though

Are most of the members on here from the US or UK would you say?

 

[Sean Matthews]

Read this article ; all basics are welll reminded but .......;
There is something strange writed on the gelcoat procees to do ;

• Once cured, sand down the surface and remove any imperfections ready to lay up the first layer of fibreglass.

In any case don't do that!!!!!!! gelcoat need to cure and stay tacky and then you start laminating
It's strange to read this phrase because below you can read read another expalanation ????? so probably some wrinting mistake ????
But have to be corrected because people doing that sand onto the gel will destroy all the work and maybe damage the mold or the plug !!!!

Jusst my 2 cents

Hi Michel,

just reading this back, and you are right, there isn't any need to rub it down, I am not sure what has happened, here, I think I have my wires crossed somewhere when editing this section.

Thanks for pointing this out, I will make sure I update it !!

 

[Randy V]

Thanks Randy, yes of course, proud to say I got to work on a GT40 a few years ago, and loved them since. Never been able to afford one though

Are most of the members on here from the US or UK would you say?

I don’t really have the numbers to lay out the demographics, but I would guess that of GT40 owners here we probably have 50% based in USA and the rest are in Europe and down-under..

 

[Michel]

May I add some "tricks " to help beginners not to go on some little issues ;

1// To be sure that the gelcoat will not be melted with the first lay of resin ; it's advisable once the first lay of gel is cured to paint another thin lay of similar gelcoat and let it cure . this prevent absolutly to get those bad small "freezed " areas sometime a mold (or a part) can get
2/ Before the first strand mat is layed on edges , to help this stuff to conform sharp edges or corners it is advisable to lay some resin added with aerosil white compound ( like a yogourt paste ) on every area where it seems difficult for the strand matt to conform edges ; when done lay immediatly the clothes and roll with caution with a bubble roller using it from center to external lines to pusch out any air trapped
3/ When using steel or wood rinforces place some cardboard strips ( or better some special "feltrine " stripes) in beetween faces of the rinforce and the mold surface where they joint . this prevent those rinforces some weeks after to sort of print a "shadow" or a"swallow" thru the thickness of the mold
into the gelcoat aspect and will ruin all the work , as this shadow will appear also ont the parts !!

Hope this helps
An apologise a lot For "hacking " this usefull thread !!

 

[Sean Matthews]

This all sounds like great sensible advice, thanks for your input

 

[Hector]

This entire thread is super helpful. I wish I had seen it before I made several fiberglass parts, I had to figure out all those details the hard way, by messing up and having to re do things several times.

A must read for anybody making custom molds and fiberglass parts. The entire process can be used using modeling clay as the first step, that is how I made my center console and modified the front clam to accommodate Jaguar headlights on my SLC.

Have a great 2024 and best wishes for successful fiberglass fabrication to all of you, as a complete fiberglass neophyte I can tell you , don't be afraid and dive in, seeing a finished product of your own creation is super cool.

 

[Terry Oxandale]

Welcome Sean. Thanks for the "intro". Did my own fiberglass body, so I appreciate your contribution.