|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Hi all, Here is an update on the project. Finished polishing with compound as in figure #4 (previously sanded gloss finish with 240, 320, 400 and wet 800, 1200, 1500). Made a barrier for split mold, applied 5 coats of release agent and used filleting wax (figures#3, #2). Glassed obviously one side at a time with two layers 100g and 4 layers 400g with polyester resin (mold on a budget). Glassed supports for when the mold is flipped over (figure #1). Now tomorrow will be the really scary part: unmolding...
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Thanks again for all the great advice and support.
|
|
|
|
|
Hanaldo
|
|
|
Group: Forum Members
Posts: 2.5K,
Visits: 28K
|
Zedok (29/06/2015)
Many thanks Hanaldo and Dravis for your comments and encouragements. At least my observations are normal and I have not f***ed up... yet. I have ordered a set of orbital 240, 400 and 800 orbital discs which should make the job easier. Spraying is not an option at this point. Anyhow, I would have to take time and learn how to spay correctly. Might as well take that time and sand. The idea of thinning the Gloss resin with 8% acetone seems very appealing and I shall have a try on a small part of the the pattern. Hanaldo, you mentioned: " Fortunately, it's easy to fill these little holes and sand smooth. " Do you mean filling them with additional gloss resin? Cheers, Z Yeh mate, just mix up a small amount of the gloss coat and and use a pop stick to dab it into the holes. Fill it proud of the surface so you can sand it down flat. Easy as.
|
|
|
|
|
Dravis
|
|
|
Group: Forum Members
Posts: 592,
Visits: 1.9K
|
Yeah .. excellent advice that ... polishing and wet sanding should be done in between other jobs .. otherwise it becomes (in the immortal words of the chartered accountant in Monty Python  ) "Dull.. Dull. Dull... So DESPERATELY DULL ..."  
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
|
|
|
|
|
VVS
|
|
|
Group: Moderators
Posts: 226,
Visits: 334
|
Keep up the good work, you will come good in the end.
Do a bit then walk away and come back fresh.
I'm polishing three moulds and sanding two plugs at present, they are much smaller than your hull but quite tricky so I give them an hour then take a 10min rest and come back with fresh eyes, I want them perfect so am now down to 2000 grit paper before buffing.
will look trick when finished and you will feel 100% after doing it yourself.
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Many thanks Hanaldo and Dravis for your comments and encouragements. At least my observations are normal and I have not f***ed up... yet. I have ordered a set of orbital 240, 400 and 800 orbital discs which should make the job easier. Spraying is not an option at this point. Anyhow, I would have to take time and learn how to spay correctly. Might as well take that time and sand. The idea of thinning the Gloss resin with 8% acetone seems very appealing and I shall have a try on a small part of the the pattern. Hanaldo, you mentioned: " Fortunately, it's easy to fill these little holes and sand smooth. " Do you mean filling them with additional gloss resin?
|
|
|
|
|
Dravis
|
|
|
Group: Forum Members
Posts: 592,
Visits: 1.9K
|
I've just finished a plug and a mould for a GSXR Dragbike tank cover, I had the same issues with the High gloss Pattern coat, stripey and rather uneven, even on top of a completely flatted down cover of Pattern Coat primer. (I can paint 2-K boat varnish with the type of brush I used, to a level that looks like it is sprayed on ... I've had years of practice on boats ...) I also had to use 240 grit on a circular sander to speed up my work.. I had to sand so much down that i broke through the high gloss i a few small places, so I decided to try spraying the High Gloss, using the Gel-coat cup gun.. That actually worked MUCH better, the second coat was much smoother  But it still had som areas of "orange peel texture" I sanded this down using dry 400 grit, then went up to 1500 wet sanding .. I Polished only with coarse compound, since I wanted a satin finish in the plug and mould. The (Unimould) mould came out very nice, even though I was in a dreadful hurry and did the whole process in less than 24 hours.... I then did a small test, and thinned the High Gloss Pattern Coat with around 8 % Acetone ... then brushed it on ... MUCH better result ... Might be worth a try, If you can not spray your plug...
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
|
|
|
|
|
Hanaldo
|
|
|
Group: Forum Members
Posts: 2.5K,
Visits: 28K
|
It's very difficult (ie. virtually impossible) to get a smooth finish when brushing a coating, it will always be uneven no matter how well it self levels. The small holes are likely to be air as again, it's difficult to brush a coating without trapping even a small amount of air. That said, it is also possible it is solvent outgassing, of which you can do very little about. Fortunately, it's easy to fill these little holes and sand smooth. Unfortunately, there is no real easy solution to the task unless you can spray your coatings. If you have the equipment and ability to spray, this will greatly reduce the amount of sanding work you need to do. If you can't spray, then you are committed to a lot of sanding hours, and you'll have to accept that you CAN'T go for the quick option of sanding down with 120. You will need to sand down with 320-400 until flat, which will take a long time. On such a large job, an orbital sander wouldn't be a bad investment. It's simply a case of sanding and coating and sanding and coating until you can get the surface flat without rubbing through the coating. Then you can move through the wet sanding stages and finally compound. It's the worst part of the job and I don't envy you for the size of your task, but it's a great feeling when you're finished!
|
|
|
|
|
Zedok
|
|
|
Group: Forum Members
Posts: 18,
Visits: 115
|
Hi all. Well my pattern is finished and I have applied a coat of Pattern-Coat Hi-gloss. Here are my issues: 1) Although the resin is supposed to have good self-leveling properties, I notice that there are unevenness when applied. This requires additional sanding with 120 or 180 grit paper (Picture 1 shows partly sanded side surface of the pattern). 2) There are little depressions on the gloss surface approximately 1-2mm diameter. I assume they are popped little bubbles (Picture 2). I was careful not to add air in the resin whilst missing and I used a reasonably good brush. Are these issues due to the type of brush that I used? Have I applied the resin too quickly too much at one time? Anyhow, I did not expect to have have to go back down to 180 or 240 grit after the gloss. Any comments on where I am going wrong? Thanks.
|
|
|
|
|
Dravis
|
|
|
Group: Forum Members
Posts: 592,
Visits: 1.9K
|
Looking good 
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
|
|
|
|