Application of tooling gelcoat

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#1

Hi to all, I am building a 33 feet ( 10 meter) boat hull mold and will soon have to face the covering of the plug with tooling gel coat, So far our attempts to apply it by brush have been relatively successful, but we believe that it really really is something very difficult to do, since the first coat must be relatively thick (500 microns) and the material is what we call ( as the opposite of friendly) an hostile material which totally refuses to cooperate we never managed to achieve a relativeley uniform thickness ( despite there being videos in youtube showing how is done and looking easy).

We will buy an airless gelcoating machine ( glascraft ) next week but much to my surprise, despite there existing in the market several renowned brands that offer tooling gelcoat for spray application, it seems that almost nobody uses it, most of the users of tooling gelcoat favouring its application by brush.

For the size of our job and having found brushing to be an almost impossible way due to its inherent difficulties I wonder why is it that ( at least here in europe ) people does not use the tooling gelcoats formulated to be sprayed instead of the extremely difficult and inconsistent method of brushing it.

This is what we are making: …

#2

I would use Duratec Vinyl Ester primer. Easy to sand will buff out ect.

#3

Yes, we will be applying some Duratec first but when the plug is ready to tooling gelcoat I need to have solved any doubts and taken decisions about what to do with a certain amount of time in advance, thank you for trying to avoid us a costly mistake

we believe that for the size of our hull and other pieces we have no way to escape from buying a proper gelcoat dispense airless spray system, primarily for the application of the boats and pieces gelcoat but having the machine we would like to use the system for the application of the tooling gelcoat as well instead of brushing it over our male plug, bear in mind the large surfaces to be covered …

#4

No one willing to give some help here ???

#5

no one willing to give some help in this forum ?

#6

Sorry I guess I missed this thread. I’ve never used DSM products before but they are from Switz and can be sprayed.
http://www.dsm.com/nl_NL/html/drs/gelcoat.htm
Around 6:30 they get to the gel coat application.
[ame=“http://www.youtube.com/watch?v=pDzAdBZg0vc”]Tamarack Fibreglass Production Facility Tour (Loon Solar Boat) - YouTube[/ame]

#7

Sure, but you did not ask a question…

I guess about 75% of the tooling gelcoat we sell is spray version, so I guess that is part of the answer.

Both with spray or brush gelcoat one can get good quality moulds. Indeed the aplication by hand (roller) is more laboursome, but at least you do not need equipment.

In both cases check the thickness of your coat regularly with a wet film thickness gauge. You will very probably need 2 applications (both with brush or spray) to achieve the correct film thickness.

Problem areas are the strakes. make sure you end up with enough but no too much material on both sides of the strake, and that there is no accumulation of gelcoat on the inner corner.
Also keep in mind the correct spray angle relative to the surface you are spraying, about 60 degrees. Too small an angle will blow waves in the gelcoat, and can create porosity.

Let the gelcoat cure thoroughly before continuing, to prevent print.

-perhaps you need to add some letters here and there in my message, I fried my laptop a week ago, and have a borrowed one now, but far from perfect keyboard in it… (and screen is not much better)

#8

Hi Herman, in regards to asking I said “I wonder why”, but anyway, for some strange reason here in spain and also in the UK the application by brush is favoured (despite being a quite impossible feat), but yes as usual, your answer says it all 75% spray, we will spray it then following the instructions to the very letter, very likely we will rely in a CCP iso/npg product.

#9

Oh, one other thing. If you sray (or roll, for that matter) gelcoat into a mould (not onto, so for now you are good to go) keep in mind styrene sinks. And a “blanket” of styrene wil inhibit cure. make sure you can ventilate the inside of the mould when the time is there. Hanging a large dia (200mm hose into the boat, and suck the air/styrene mixture out is the most simple way, if you are not planning to turn the mould on its side.

I have no experience with the CCP gelcoats. ISO-NPG should be OK, although VE is favoured over here, unless price is critical.

#10

Here’s what we use . http://www.esmfg.com/g100_cup_gun.html

#11

Hi Brad, the surface of our mold plug is 50 m2, in case of using a cup gun, there would be a need to prepare a lot of batches because for example a coat of 1mm or 1000 microns which is adequate for our tooling gelcoat means 50 kg of the product to be sprayed, which will surely mean a hundred of mixes of 0.5 kg I believe that for our surface we were in need of a spraying/mixing system.

#12

Yes, buying decent spray equipment is a good decision. Mastering it is a learning curve, both in use and maintenance, but you will manage.

#13

Your right Jigger, 50m2 it a lot for one of those guns!!