Dec 30
Fiberglass Mold Release – PVA Pros and Cons
posted by: Steve Jones in Uncategorized on 12 30th, 2017 | | No Comments »

I have received many questions from those who purchased my manual set regarding mold releases. Especially when preparing the plug. The bulk of the questions seem to come from the use of PVA as a mold release.

Let me start by saying that I like and prefer to use PVA (polyvinyl alcohol) mold release at all stages of my projects – both to release the plug and my parts. I like the security it provides. I have never had a part or a plug get stuck in mold when I have used PVA.

The problem that some people have with PVA is the orange peel appearance that is left on the inner surface of the mold after you have separated the plug from the mold. More often than not this orange peel is visible but can’t be detected by touch. Unfortunately, sometimes the orange peel appearance can transfer to the parts that you will make with your mold.

For me, this orange peel appearance has never been a problem because of the type of projects that I like to build. If you are planning on painting your finished pieces, as I do, the orange peel look of the gelcoat is of no concern. You will be at the least priming and painting the parts so you will never see the gelcoat. Even with R/C boat hulls that I have made I always plan on painting them for the final finish.

If you want to produce finished parts that have that glowing perfect gelcoat surface you will need to take a different approach with the plug. You will have to rely on mold release wax alone to allow for the separation of the plug from the mold. With this approach, you will want to follow the waxing procedures outlined in my manual. Use great care with applying and polishing the plug.

Another consideration with an approach that doesn’t involve the use of PVA is that more than likely you will damage (if not destroy) your plug when you de-mold. This is another reason why I like using PVA – I work hard on the plugs that I build and I like to save them.

I hope that this helps with your PVA questions

1/10 Scale Radio Controlled Fiberglass Mach 5

1/10 Scale Radio Controlled Fiberglass Mach 5

Happy Glassing


Dec 29
Fiberglass Finishing Microballoons
posted by: Steve Jones in Uncategorized on 12 29th, 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


Dec 26
RHIB – Fiberglass build continues……
posted by: Steve Jones in Fiberglass Boat on 12 26th, 2017 | | No Comments »

I don’t know about you guys, but sometimes my work gets in the way of my projects – I hate it when that happens! Anyway, I had not taken photos of my sketches for this project at the time of my last post. I will post more pictures with more text this weekend.

Read the rest of this entry »

Dec 24
Building Fiberglass Fenders: Part III
posted by: Steve Jones in Fiberglass Fender Project on 12 24th, 2017 | | No Comments »

With the recent application of bondo leveled and cured, I can now smooth out the surface of my fender – again. As it turned out, the two outer thirds of the circumference of my fender were about the same height. The middle section was about ¼ to 1/3 inch on the shallow side. It is in this center section that I need to reshape the fender around my newly formed ridge of bondo. I accomplish this with more bondo and a credit card that I use as a spreader. I like using credit cards or other thin pieces of plastic as spreaders because they can be used to produce a flat smooth surface or a nice smooth curved surface. Read the rest of this entry »

Dec 23

With all of the buck stations in place, I can examine the two halves of this project for symmetry. The best way to do this is by clamping the two halves together and carefully examining the big picture. I also use a ruler and check the basic measurements of buck stations that I consider critical to the final outcome. These don’t have to be perfect, but it should be pretty close, more symmetry at this point will insure Read the rest of this entry »

Dec 20
Why Vacuum Bag Fiberglass Parts
posted by: Steve Jones in Fiberglass Tips & Trix on 12 20th, 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 »

Dec 18

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




Dec 17
Fiberglass Boat Build- Keel, Hull and Sides
posted by: Steve Jones in Fiberglass Boat on 12 17th, 2017 | | No Comments »
In the post before last, I had begun to cut out pieces for the bottom portion of the hull of this boat.

As I studied the layout of the bottom of the hull, I identify the important features that I want to maintain throughout the building of this model. Obviously, an outline of the hull Read the rest of this entry »

Dec 15
Fiberglass Mold Construction Part 9
posted by: Steve Jones in Uncategorized on 12 15th, 2017 | | No Comments »

I let this mold cure on the plug for almost a week before demolding. This mold popped off its parting board with little effort. Likewise, the mold separated from the plugs with ease. The process for removing the mold from the plug is simple. I use a half dozed small plastic putty knives that I insert between the mold and the parting plane.

Once I have one putty knife between the mold and the parting plane, I simply insert another putty knife at the edge of the separation that occurred as a result of the first knife. This is repeated time and time again as I work my way around the perimeter of the mold. Once you get started, this is an easy process.

At this point the mold is inspected for any flaws, repaired and then prepped for its first part pulls.

Making parts with this mold is very similar to making the mold itself. I begin by applying five coats of mold release wax to the inside of the mold. Once the mold is waxed, I can apply a coat of PVA to the inside of the mold with my spray gun. After the PVA dries, I can do my first parts lay-up. This is part that I really enjoy – I am very close to seeing the results of my efforts and planning.

Happy Glassing


Dec 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.

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