what do we really know about gel coats ??

[tunnels]

Gel coats have changed considerably during my time !!
When I started work all gel coats were brushed on ! This was a job that different places I worked had different technique's and ways of brushing, Long stroked always in the same direction and brushed a minimum of 6 times then dip the brush for another load and brush 6 times
Things like porosity were unheard of, pigment separation was sometimes a problem, Brushing tooling gel using the 6 times brush strokes made some of the most shiniest moulds ever , I have never seen mould like them since those early days.
A second coat was always applied AND the catalyst was raised from 1.5% to 2.0% always, so had to be really fast at putting it on !

Pigments were a big problem and caused strange brush marks if you were using mixed colours ! so the company only ever used white that's all !!
The second coat could also be applied with a mohair roller and the trick was to used a little amount of laminating resin with the mix to make it flow out smoother on the surface once its gone hard , This is something I still use to this very day if I happen to be brushing any gel coats !

Then we were introduced to the pressure pot to spraying gel coats and oh boy there were lots of teething problems that came with it mostly to do with the equipment used ! People had the pet settings and nozzle sizes they used .
One big problem was gel times and the actual amount of time it took to spray a job and oh dear its going off in the pot and the hoses are
gel-ling and panic and chaos ! . Was quite amazing the number of guys that could spray but did not understand all the working of the gun and pot as a unit ! there were some terrible disasters and spent hours drilling and soaking and cleaning etc
It wasn't until much later I could see there was a need for a better set up so I started making my own using an additional pressure regulator that made life so much easier and cleaner to work with .

A while later Venus appeared with a professional gel coat spray gun And this was heaven to use , with the quick change nozzle size could spray almost anything in super quick time! , Big nozzle for hulls and large flat areas on decks then change to a smaller nozzle and so all the small areas
Inline heating units became the thing and that was a big step and sprayed warmed gel coat that gave a glossy finish to the surface !

As always with all this new technology and fancy equipment to speeding up application and production came a whole raft of new problems we'd never seen before and no one knew what the causes were , so a very steep learning curve as to the possible causes could be !.
It was so easy to spray to much product onto a mould and things like drifting and colour separation !,and veiling!, along with pre-release in and along the corners !
that is why people that are good gel coaters are artist and need to have the magic touch needed to recognise and know what they are doing 100% of the time !!

Before the days of stick on decals stripes , two toning was done by masking and spraying one colour then unmasking before it was hard so the next colour could be sprayed at the right time .
Clever gel coaters realised it was also possible to spray the second colour very carefully while the first colour was still wet so that speed up the whole process . The guys that did this kind of work were true professional's in every sense of the word but keep there secrets to themselves always !
It took some clever Tahitian guys I worked with to show me how it was done with primitive old out dated equipment . Its really all about timing and gel times and understanding how gel coat gels and how it goes hard , product knowledge !!

The gel coat manufacture we had in nz had a completely new range of different colours and asked if I could make a sample display ,so I used this to demonstrate and showed my gel coat guys that it was possible spraying 6 different colours in quick succession wet on wet and unmasking each area as I went .
This is a dead art that I know of no one does this any more .

Gel coating and gel coat repairs is a whole subject on it own ! and after collecting a few photos will be my next Question and answer quiz as to the causes of the various problems !!Please remember there is usually never just one single cause but a collection of things in some cases so will be time to do a little thinking

[dwilfong]

When I did glass work back in 1980 we mixed are own gel coat. Talcum powder and powder pigment mix in resin.
It was mixed one cup at a time and put on with a spitter gun.
We had one guy that was responsible for the molds and gel coat. That way he had no one to bitch at when it did not pop off good. He waxed and repaired all the molds. Then did all the prep for the gel coating. PVA was used on all the molds for release agent.
He had his gauge in hand all the time to check how much he put on.
The gel was all mixed up in one batch.
He would line up the cups and activate them one at a time as he need them.
With 50% peroxide it did not take much.
He could do a 30' x 10' mold for a alcohol grain mash separator lid in no time at all.

[tunnels]

[QUOTE=dwilfong;2962041]When I did glass work back in 1980 we mixed are own gel coat. Talcum powder and powder pigment mix in resin.
It was mixed one cup at a time and put on with a spitter gun.
We had one guy that was responsible for the molds and gel coat. That way he had no one to bitch at when it did not pop off good. He waxed and repaired all the molds. Then did all the prep for the gel coating. PVA was used on all the molds for release agent.
He had his gauge in hand all the time to check how much he put on.The gel was all mixed up in one batch.
He would line up the cups and activate them one at a time as he need them.
With 50% peroxide it did not take much.


Those were the days !! but we learned a lot during those rude crude things we all did .
Those crude spatter guns i have taken out side and hurled quite a few into place where where they will never be found if ever !!!I was handed one to do some gel coating and threw it on the floor and walked away in disgust !

[dwilfong]

[QUOTE=tunnels;2962046]

When I did glass work back in 1980 we mixed are own gel coat. Talcum powder and powder pigment mix in resin.
It was mixed one cup at a time and put on with a spitter gun.
We had one guy that was responsible for the molds and gel coat. That way he had no one to bitch at when it did not pop off good. He waxed and repaired all the molds. Then did all the prep for the gel coating. PVA was used on all the molds for release agent.
He had his gauge in hand all the time to check how much he put on.The gel was all mixed up in one batch.
He would line up the cups and activate them one at a time as he need them.
With 50% peroxide it did not take much.


Those were the days !! but we learned a lot during those rude crude things we all did .
Those crude spatter guns i have taken out side and hurled quite a few into place where where they will never be found if ever !!!I was handed one to do some gel coating and threw it on the floor and walked away in disgust !

In the hands of a person that has experience with it he will use nothing else. Easy to keep clean just toss the cup and run some acetone threw it. The tips are changeable and different sizes. It take a special talent to use one that is for sure. I could not get the hang of it. I tried to fill in when he was out one day. That did not go so well. what a Fing mess to clean the mold off. I thought he was going to kill me when he got back and seen the mold. Lets gust say there was lots of clay on that mold till he repaired it. The PVA is also hard to spray even. I got the hang of that to help out some. Took some time to get use to the 50% peroxide also. We had a trash can in the middle of the shop with noting in it. It was the hot mix can. I used that a lot a first also. You need to get that cup in there fast or your hand got blisters. Dixy cups are no fun with a hot mix in them. We where doing direct injection resin molding at that time. this was before vacuum bagging. It was the new thing the Japanese where testing for boat building.
You built a two piece mold and put the cloth in side. Then you pumped the resin in the mold from the bottom. There where vent tubes in mold. When the resin started to flow out the vent with no bubbles you clamped of that hose. Was hit or miss as you hade to pump slow and stop from time to time for the resin to soak in good. It was blind mans bluff. You had to imagine in you head the resin flowing in the mold to get it right. I had good luck with that as my mind was under the influence of let say expanding drug at that time in my life.......LOL
It was like Christmas ever time you cracked the mold open. Just hope there was not coal in the mold.
Yes the good old days......when putty was made with asbestos powder......LOL

[tunnels]

[QUOTE=dwilfong;2962063]

In the hands of a person that has experience with it he will use nothing else. Easy to keep clean just toss the cup and run some acetone threw it. The tips are changeable and different sizes. It take a special talent to use one that is for sure. I could not get the hang of it. I tried to fill in when he was out one day. That did not go so well. what a Fing mess to clean the mold off. I thought he was going to kill me when he got back and seen the mold. Lets gust say there was lots of clay on that mold till he repaired it. The PVA is also hard to spray even. I got the hang of that to help out some. Took some time to get use to the 50% peroxide also. We had a trash can in the middle of the shop with noting in it. It was the hot mix can. I used that a lot a first also. You need to get that cup in there fast or your hand got blisters. Dixy cups are no fun with a hot mix in them. We where doing direct injection resin molding at that time. this was before vacuum bagging. It was the new thing the Japanese where testing for boat building.
You built a two piece mold and put the cloth in side. Then you pumped the resin in the mold from the bottom. There where vent tubes in mold. When the resin started to flow out the vent with no bubbles you clamped of that hose. Was hit or miss as you hade to pump slow and stop from time to time for the resin to soak in good. It was blind mans bluff. You had to imagine in you head the resin flowing in the mold to get it right. I had good luck with that as my mind was under the influence of let say expanding drug at that time in my life.......LOL
It was like Christmas ever time you cracked the mold open. Just hope there was not coal in the mold.
Yes the good old days......when putty was made with asbestos powder......LOL

Like I said I refused to use them God awful things so have made many pressure pots with parts I've always found most companies have stuffed away in boxes in there store rooms .
Korea made two systems exactly the same for there two factories !. ,
Here in china found a big box of guns and fittings and a pot that was all grubby and covered in gunk ! so spent a few days and behold a complete system !!. Plus enough bits and made a small unit specially for repairs and speckle jobs and painting with ! Using plastic drop on containers saves lots of cleaning and acetone and if you doing multi-coloured speckle jobs can have all the colours lined up one after the other in quick succession and only clean once at the end of a job !
Another company I found a big wooden box filled with derelict Binks guns basically the same model so after scratching through the bits built 4 complete guns complete so swapped the one they were using everyday for a nice clean oiled and working perfectly new gun ! The gel coat guy thought it was xmas . So as an excise we stripped and cleaned his old gun to like new status also . Then taught him the workings and how what everything was for and how to take special care of all his equipment ! Pride of his department paid dividend's with no more stoppage's and his workmanship improved as well as he took pride in everything he had to work with and a far better understanding of how everything worked .I am a firm believer that if you can see just one spot of gel coat any where on the gun its not clean enough!!at the end of each session the gun needs to be totally stripped apart cleaned and left to soak in a sealed plastic container till next time !

[Slimm]

I love reading these stories! I love working with glass but have a very rudimentary understanding and experience limited to just building small to medium enclosures for speakers from 1"-18" in size for car audio. I would love to learn how to make molds and produce parts that are different colors. I also want to get a grasp of all the different cloths and what each number or type is used for as well as how to best mix types of cloth for strength and weight etc..

Keep the info coming, it's not going to waste.


Slimm

[Murph]

Been using the 3M PPS Paint Preparation System for a couple of years now.
Sweet System, it's like having a pressure pot in your hands.
Pretty much full proof if a batch kicks off.
Just pull apart and clean tip, the rest is disposable.
Straight gel or with additives, just change tip size.

[tunnels]

Been using the 3M PPS Paint Preparation System for a couple of years now.
Sweet System, it's like having a pressure pot in your hands.
Pretty much full proof if a batch kicks off.
Just pull apart and clean tip, the rest is disposable.
Straight gel or with additives, just change tip size.

Will it spray upside down inside of a boxed area ??

What is meant by gel coats and additives ??mmmmm!
Gel coat is just that its not paint and doesn't behave like paint not matter how you try to change it with the many additives that people add to it
things added for thinning or stuff added to dilute ?? there's a big difference and one is preferred over the other with very good reasons why !,
And for a toy gun of that size if a brew gels then what have you been doing with just one cup of gel coat ??
Even a good sized 6kg to 9 kg of gel coat in a well set up pressure pot its possible to unload the lot onto a big mould and still have time up your sleeve to clean the whole system completely no sweat and have a cup of tea with in the gel time !.

[XstreamVking]

3M's system is neat and easy to clean using very little solvent. Pressure pot is a PIA. Wastes material and has to be cleaned with a lot of solvent. No comparison. For small jobs I would use the 3m cup gun.

[tunnels]

3M's system is neat and easy to clean using very little solvent. Pressure pot is a PIA. Wastes material and has to be cleaned with a lot of solvent. No comparison. For small jobs I would use the 3m cup gun.

yes have used the 3M system and all the disposable bits and I will agree its a need set up ! My son in the air force used them all the time for the work he was doing its where I saw them first !
I guess im a die hard and have used pressure pots for to long ! waste is what you make your self . use no more thinners than a ordinary spray gun . Small jobs use small pressure pots . have made many from those 1 litre pots that are always laying around no one seems to find useful . Just set them up with all the same bits including the gun off the bigger pots and like have said before with the addition of a extra pressure regulator they are simple easy and good to use !
Always use drop in plastic pots for product no mater what you want to spray , gel coat , paint , lacquers , varnish, speckle coat what ever all done with one single pot and gun set up !. 1 liter or 6 liters same system same bits just one adapts to the other ! 3M has a limited use !! . And even with the disposable bits still needed thinners to clean it with so the cost of thinners AND the cost of the disposable's ?? each time its used ??

[One Oldman]

While I don't care all that much about appearance and really can't add much to this conversation, since my only experience has been brushing and rolling of gel. I do have a few questions that might be appropriate here. The few times I have used it I wound up with a slightly tacky finish in spots. My question is has anyone tried to roll or brush on gel with 'traction grit' mixed in?

[XstreamVking]

Thin spots will not cure properly, you need a more uniform thickness. Also need wax solution additive, and 2% hardener for cure. Applying non-skid with a roller works two ways, you can roll out the gell and while wet, sprinkle it on with a salt shaker type container and then roll a 2nd coat of gell on after it dries. Or mix the particles into the gell and roll it on. More grit, rougher the surface. I prefer the 1st way myself as you have better control of the final finish. Hope this helps...

[Murph]

yes have used the 3M system and all the disposable bits and I will agree its a need set up ! My son in the air force used them all the time for the work he was doing its where I saw them first !
I guess im a die hard and have used pressure pots for to long ! waste is what you make your self . use no more thinners than a ordinary spray gun . Small jobs use small pressure pots . have made many from those 1 litre pots that are always laying around no one seems to find useful . Just set them up with all the same bits including the gun off the bigger pots and like have said before with the addition of a extra pressure regulator they are simple easy and good to use !
Always use drop in plastic pots for product no mater what you want to spray , gel coat , paint , lacquers , varnish, speckle coat what ever all done with one single pot and gun set up !. 1 liter or 6 liters same system same bits just one adapts to the other ! 3M has a limited use !! . And even with the disposable bits still needed thinners to clean it with so the cost of thinners AND the cost of the disposable's ?? each time its used ??

3M PPS will spray upside down, sideways and just lay it on the floor if you need to.
They have 1 litre pots but my hands are a little wore out these days to hold them up.
You can easily spray big jobs with the 6oz pots.
I line up as many 1 litre pals as needed.
Add hardener to 1 litre, pour into and cap 4 - 6oz liners.
With the quick change you have lots of time to blow out the 4 - 6oz liners and repeat.
I just throw the liners into a pal of acetone to clean up and reuse many many times over.
The tips can also be used over and over but the spray pattern quality decreases some.
Not an issue when spraying the molds.
Just use a new one to spray as small as a 2-3" circle for little little repairs.
Very versatile and time saving system.

[One Oldman]

It has been a while, but I am pretty sure I had the MEKP right and added wax. Thin application most likely the problem.