Hello all.  I have made a mould using the Uni-Mould system.  The pattern was finished with Pattern-Coat High-Gloss, and had some scratches (I had started with 80 grit).  But I made the mould anyway and the scratches, as expected came through.  So the scratches on the mould were now male scratches and easier to remove.  So this time I started with 400 grit wet (wet, circular motion, 3 sessions), followed by 800 (wet, circular motion, 2 sessions), followed by 1200 (wet, circular motion, 2 sessions).  Attempted polish with Topfinish2 and medium/soft blue pad in DeWalt polisher, but ended up with deep scratches.  Also have attempted NW1 cutting compound with medium/hard orange pad, still no cigar.

I have ordered 1500 and 200 grit, I will start again at 800 grit and go through 1200, 1500 then 2000. And then probably NW1.

Any other suggestions? You can clearly see the scratches in the pictures, the phone camera picks them up really well. In the third picture, you can see how rough the surface is in the light section. One problem is that the entire mould is concave, but my pads are flat.  Are there hemispherice pads available anywhere?

For those mould scratches, NW1 is the way to go.  Also you need to ideally be at 1500 grit or better. TopFinish is a medium to fine cut and as such 1200 grit is way too coarse for it to remove the scratches.  NW1 is recommended from 1200-1500 grit and upwards.  If you are picking up MORE scratches polishing then there is either grit in the pad or on the surface and/or your polishing technique is too aggressive.  For complex shapes like that, you can if you want, carve the pad or abrade the pad away to curve it to fit  - some softer pads with heavy wear end up like that naturally.  An alternative would be to move down to a smaller pad such as the 80mm version of our Medium/Hard (Orange) Polishing Pad which should be a lot easier to handle on that mould. 


Wayne, sorry to hear you are struggling so much with polishing the GlassCast 3. Something is definitely going wrong somewhere in the process.  We have a lot of customers successfully polishing the resin back to a high gloss, some with our polishes, some with other brands, so if everything goes right you should be able to get a good finish.  First thing is ensure the resin has had plenty of time to harden properly before sanding and polishing. NW1 is designed to work from 1500 grit upwards so 3000 grit should be plenty smooth enough. 

Sanding can sometimes take a lot longer than you think working through each grit to remove the scratches from the previous one.  You need to be very careful on avoiding transferring dirt or grit as you move finer through the papers, otherwise the grit will cause more scratches.  Also take care to avoid skipping grits or moving too soon to the next grit before you have fully removed the scratches from the previous grit. Once you are 100% confident you have got a minimum of 1500 grit evenly throughout, then you can move onto polishing.

NW1 is self lubricating so no need for water.  Also, it is easy to apply too much in one go.  As the polish is a diminishing abrasive, it starts coarse and gets finer, so if you have too much, you end up smoothing the surface initially then accidentally rubbing the unused excess polish back onto the part scratching it up again as you put coarse grit onto a partially polished surface.  Don't go too mad on the polishing speed and try not to work on too large an area in one hit.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant