Aug 30
Why Vacuum Bag Fiberglass Parts
posted by: Steve Jones in Fiberglass Tips & Trix on 08 30th, 2017 | | No Comments »

One way to make light, strong and clean parts is through a technique called vacuum bagging.  In general, parts made with vacuum bagging techniques show better strength and stiffness than simple molding lay-ups and they are smoother to the touch.  The strength and stiffness of vacuum bagged parts obviously comes from  Read the rest of this entry »

Aug 29
Tooling Gelcoat for a High Gloss Finish
posted by: Steve Jones in Fiberglass Tips & Trix on 08 29th, 2017 | | No Comments »

I’ve received some more questions about Fiberglass Mold Making Gelcoat and how to end up with a high gloss shiny finish.

Sonic 1 High Gloss

When constructing a mold for duplication of parts, there are several considerations that must be addressed.  The main reasons for using tooling gelcoat versus finishing gelcoat have to do with the hardness of the finish and the shine of the finish.

The finished surface of your mold should be abrasion resistant.  Polyester gelcoat is used for making tooling masters and molds where good gloss retention of the surface is of paramount importance.   A high gloss finish of the molds surface allows for easier release of your parts and thus extends the life of the mold. Read the rest of this entry »

Aug 26

Continuing with the helicopter build …


At this point, I can begin to produce profile drawings of the copter.  I definitely need to start with a view from the top and a view from the side.

Some of this is accomplished through artistic ability and some of it is what I consider cheating.  The model that I bought had these views in the painting instructions.  Based on the diameter of the fan blades, I figured that the fuselage should be about 40 inches from nose to tail.  I simply used my copier to blow these views up to the size that I need.  Then I drew in some details that were lost in the enlarging process.                            


The next step for me was to trace these profiles onto a base that I can use to build a plug.  I like to use 1/8 inch mahogany door skin for this.  I like mahogany because I can buy it at home depot for cheap and one sheet is more than enough material for a project like this. 


Next, I want to decide along which line to epoxy the primary horizontal shape to the vertical shape.  Having access to my plastic model makes this decision easy.  Angle aluminum stock helps me align the mahogany pieces with each other.  I use the angle aluminum to clamp the pieces to each other which assures reasonably accurate alignment of the parts.


In addition to angle aluminum making alignment of not so straight pieces easier, it also gives a pretty good 90 degree alignment of one piece to the other. 


At this point I need to make a statement concerning scale.  I am no artist, I know from the outset of a project like this that when I am done, anyone who knows anything about helicopters is going to look at this and say “Hey, that’s a Huey UH-1”.  That is good enough for me.  You can put as much talent and time as you wish into a project.  This is your prerogative.  I like to get a project’s detail to the point where I am satisfied.  I think that I am usually satisfied with my projects bearing a close resemblance to the vision that I started with.  That being said, nothing that I ever build will ever be completely scale (unless I happen to trip over a bucket of talent and patience).  That is all I have to say about that.


More Soon




Aug 23
Fiberglass Model Build Part 7
posted by: Steve Jones in Uncategorized on 08 23rd, 2017 | | No Comments »

Preparing the plug is the next stage of this build. I begin by mounting the two halves of the plug to a piece of inch thick MDF board. I attach the plugs by using screws from the back side of the MDF. Some people glue or epoxy their plugs to the parting plane. I prefer to use screws because I can remove the plug from the MDF after the mold is finished with out destroying it.

Once I have the plugs securely attached to the parting plane, I need to go around the base of the plugs looking for gaps between the board and the plugs. Any gaps are filled with clay. This is just a matter of forcing the clay into the gaps in order to prevent resin from getting under the plug. When the gaps are filled and all excess clay is removed, I can apply mold release wax to the plugs and the MDF parting plane. I like both McGuire’s and Part-All mold release waxes. It is important to apply at least five coats to the plugs in order to ensure adequate coverage. The plugs should be polished to a shiny smooth finish.

PVA is now sprayed onto the plugs and the parting board. The PVA is an excellent barrier between the mold and the plug. I like to spray a coat, let it dry and then re-apply. Applying two coats of PVA can result in lost detail but that is not a concern for me with this project. An additional coat of PVA will ensure an easy release when I de-mold the plugs.

I apply the PVA with my spray gun at about 60 psi and a distance of 8 to 12 inches. PVA is cheap and valuable at the same time. This set of mirror image plugs is now ready for molding.

For the molding process I need my air compressor and dump gun along with: tooling gelcoat, fiberglass resin and chopped mat, MEKP, rubber gloves, disposable brushes and a respirator or fume mask.

Happy Glassing


Aug 21
Fiberglass Finishing Microballoons
posted by: Steve Jones in Uncategorized on 08 21st, 2017 | | No Comments »

I have written blog entries in the past in which I have shared my experiences with new techniques and new products that are available for construction with composites. This is another one of those.

Whenever I am building the surface of a part that is being made of chopped mat, I end up with a fairly course surface that will need a final finishing.

I have employed various means to smooth out a fiberglass surface. Some of these finishing methods include the following:

For some applications I use veil over the final layer of chopped mat. This method hides most of the course fibers of the chopped mat without adding an excessive amount of extra weight to the final product. In fact, when I add a final veil covering I very rarely have to add any extra resin to the finish. Usually I can use a small roller to press the veil onto the surface of the still uncured mat / resin underneath it forcing the resin to seep into the veil and provide adequate saturation on the surface. The individual fibers of veil are much finer than those of chopped mat so the final surface is smoother.

For other applications I mix a putty-like consistency combination of resin and cabosil that I use to smooth over the surface. This has been one of my favorite methods for finishing a fiberglass surface. The cabosil / resin mixture can be made as thick or thin as your project requires. Once this mixture is spread over the surface and cures, it can be sanded smooth and finished.

Sometimes I will simply skin the surface with bondo. I like bondo because it sands so easily and cures so fast. You can smooth out a surface in a hurry with bondo. The drawbacks to using bondo are that it is easily chipped / damaged and it almost cures too fast. I have wasted a good amount of bondo over the years by mixing more than I could use in its working period.

The other day I went to my local fiberglass supply store and asked for a ¼ pound of cabosil. The gentleman that helped me asked if I wanted something that would sand a little easier. I said “sure” and he suggested microballoons. The microballoons mixed into a nice white paste and spread easily on the surface of my project. It also sanded easily as promised. In addition to easy sanding, it also seems durable as it passed the hammer tap test that I performed on the tip to the bow of my boat project. It didn’t hit it full force but I hit it hard enough to crack bondo and the microballoons didn’t crack. I was impressed.

In the beginning of this article I said that I was writing about a new product. Microballoons are not “new”, they are simply new to me. Once again, we tend to get comfortable with methods and materials that are known to us and close ourselves off to other products and procedures that are available.

Fiberglass Deep Vee Radio Controlled Boat

Fiberglass Deep Vee Radio Controlled Boat

Happy Glassing


Aug 20
Fiberglass Boat Build Continued…
posted by: Steve Jones in Fiberglass Boat on 08 20th, 2017 | | No Comments »

In my last post I addressed an issue that I was having with the plug that I am building for this fiberglass project. At some point after the sponsons were covered with mat and resin I realized that they were simply too big in diameter. To correct this problem I cut the fiberglass covering off with a Dremel tool and then used a chisel to scrape the building surface clean of foam. After rebuilding the sponsons with foam and fiberglass I begin to follow the … Read the rest of this entry »

Aug 19
Fiberglass Model Build 11 Meter RHIB
posted by: Steve Jones in Fiberglass Boat on 08 19th, 2017 | | No Comments »

To prepare this model for the molding process, the first thing I need to do is mount it onto a parting plane. My inclination is to use some nasty looking piece of scrap 1/8 inch piece of press board that I have laying around. However, since I am going to take a bunch of pictures of this process and turn it into yet another fiberglass instruction manual for my current series, I decided to use a nice looking piece of wood from the local Home Depot … Read the rest of this entry »

Aug 16
Fiberglass Boat Build Continues
posted by: Steve Jones in Fiberglass Boat on 08 16th, 2017 | | No Comments »

Now it is time to break out the fiberglass. Fiberglass resin and 1 ½ ounce mat is applied over the foam surfaces and allowed to cure. When I fiberglass over this kind of foam, I like to brush a nice thick layer of resin directly on top of the foam and then lay resin soaked pieces of mat on top of that. Like with all my projects, I allow the mat and fiberglass resin to Read the rest of this entry »

Aug 14

I have a bit of experience working with silicon molds so as expected, the mold cures perfectly and peals easily from the parting plane and the plate.  Oddly enough, the mold removed some rusted paint flecks from the plate – oh well!


With a perfect mold I go ahead and load it up with a layer of gel coat and a few layers of resin and mat.  Since this process is covered completely in the fiberglass mold manuals I won’t do too much detail on this except for re-hashing the differences between a fiberglass mold and a silicon mold.


When using a silicon mold you have to make sure that the mold is sitting on a flat surface – if the surface is curved your mold will be curved as will your final parts.  The other major difference here is that the silicon needs no prior preparation before making parts.  Simply apply gel coat, fiberglass mat and resin into the mold – no need for mold release wax or PVA.


Mold ready for Gel Coat


With a layer of Gel Coat applied I can now lay a resin and mat.


Plate is removed from the mold about 24 hrs later and is ready for paint.


This was a very simple process and in the case of duplicating a flat object like this license plate was much easier than using a traditional fiberglass mold.  Please email me at should you have any questions regarding plate duplication.

Aug 13


To begin laying up a fender, I mix about a half a cup of gelcoat with the recommended amount of hardener.  Once this is thoroughly mixed, I use a disposable chip brush to paint the gelcoat into the mold.  I try to get a heavy layer of consistent thickness.  This gelcoat needs to cure to a tackiness before I apply the fiberglass mat and resin.  Usually this takes about 45 minutes. 


While I am waiting for the gelcoat to cure a bit, I begin to prepare for the next steps of this process by tearing 1 ½ ounce mat into small pieces that will be easy to lay into my mold.  Since this is a fender, it has compound curves – one that goes side to side and one that goes front to back.  In my experience, smaller pieces of mat are easier to work with in a mold like this.  Just FYI, my pieces of mat are approximately 4” X 4”.


Now that the gelcoat has cured to a tack, I mix an 8 ounce cup of resin and catalyst (as directed by the manufacturer) and begin to work my way around the inside of the mold with resin and mat.  I soak a chip brush with resin and use it to blot the resin onto the mat over my freshly applied gelcoat.  Since the gelcoat is still tacky to the touch, it holds the mat in place while I soak it with resin.  I work my way from one end of the fender to the other and then back again (two layers of mat and resin) being careful to make sure that the mat has no air trapped underneath and that the mat overhangs the mold by an inch or so.


Once this mat and resin cure to a gel-like state (this takes about ½ hour of 45 minutes) you can safely trim the overhanging extra mat with a razor knife.  If the resin pulls or is too sticky to cut, check back in another 15 minutes and try it again.  This is the best way to clean up your parts of excess fiberglass.


After trimming, I allow the part to sit in the mold for a day or so to let it fully cure.  Once fully cured, I pop the part from the mold using a couple of plastic putty spreaders.  I simply use my fingers to pick at the part until I get slight separation from the mold then I push the plastic spreader between the part and the mold and work my way around until the part pops out.  Since I used adequate release wax and two coats of PVA, this part easily separated from the mold.  One fender down, one to go!  

My New Beach Cruiser With Fiberglass Fenders Installed

My New Beach Cruiser With Fiberglass Fenders Installed








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