Interaction Design: Resin Phase Final Thoughts (part 5)

Slightly Sanded Resin

Interaction Design: Resin Phase Introduction (part 4)

I had read online throughout this learning about failure with resin casting and the use of rubber moulds. I couldn’t find a lot of information on why it was not curing properly but most of the opinions were that resin didn’t set because of exposure to air. However the problem that I was having was the opposite, the air exposed surface dried and the surfaces that were against the rubber mould remained tacky, even after being left for over a week in the air. Regardless of whether there was no release agent, only release wax as the agent or the wax and polyvinyl alcohol (PVA) release agent, the surfaces exposed to the rubber mould didn’t cure properly, and it only seems to have been a few millimetres affected. I assume that either the resin and rubber interact somehow regardless of agents between them or it had something to do with my resin to catalyst ratios and the mixing of them, and possibly the fact that my cast was very thick.

I tried sanding off the tacky layer it wasn’t easy and didn’t work all that well, so I found workaround. Someone online suggested using the PVA agent to coat a tacky casting to protect it from air so it would harden properly on its own. I coated a couple of the resin hearts in the PVA and washed it off after about a day only to find that the surfaces were still tacky to touch. Yes, it was a frustrating process, but hey, what was I going to do? I wanted a resin heart and needed to find a way to have one. If it had come to it I would’ve done a plaster one as a last resort. Thankfully, I discovered that when the PVA dried after I had covered the hearts in it, the surfaces no longer felt sticky.

Pebeo Gloss Varnish

I had bought some gloss varnish (for resin) to coat the hearts in after and though it didn’t cure my stickiness issue when applied to the surface of the heart directly, when applied on top of the PVA layer, it seemed to work fine. So the heart I placed inside the box has a layer of PVA and then several layers of the gloss on top as protection, so it is tack-free. Not perfect but a pretty good fix under the circumstances.

As for success in future resin casting, I am going to contact the manufacturers to see if they have any pointers and then I am going to nail resin casting to the wall! In other words, I am going to end up with a properly cured piece so I can add successful resin casting to my list of skills.

Interaction Design: Resin Phase Third Attempt (part 4)

Interaction Design: Resin Phase Introduction (part 3)

I caved and bought some polyvinyl alcohol (PVA) release agent, as from what I read from various online sources it creates a nonreactive film between the mould and the resin.

I had to re-melt the rubber to make another mould. My last mould!! I left this one over night after I had released the bottle from it to make sure it was dry, though I am not sure doing this even mattered, but it certainly didn’t make things worse.

The next day I applied several layers of the release wax, in the usual way, just like the instructions on the tin. I left it to dry for a few hours after the last layer. The wax still wasn’t shiny in some places, but in other places it had a nice gloss, so I was fine with that. It seemed like I wasn’t going to get it glossy all over, no mattered how many layers I applied or how many times I made the resin object.

After it had dried, I applied a thin layer of the PVA over the entire inside surface of the mould using a small soft paintbrush. The directions on the bottle said the best method was with a fine misting spray bottle (I didn’t have one), or to use a soft cloth, but given the nature of the mould, specifically the bottle neck, a cloth would have missed areas. I’m pretty sure I only needed to apply one coat but I applied three because of concerns about the resin not curing properly the other times. I left each layer to dry for about an hour before I applied the next coat and then left it overnight again to make sure it was properly dry.

I would love to say that it worked and the resin was properly cured all over this time. It wasn’t. It was just like the previous casts, exposed surface cured, unexposed surfaces tacky to the touch.

Interaction Design: Resin Phase Introduction (part 5)

Interaction Design: Resin Phase Second Attempt (part 3)

Interaction Design: Resin Phase Introduction (part 2)

I bought some more rubber and made two moulds; using the new rubber to make one, and cutting off the surfaces from the last one and re-melting the rubber to make another.

On one, I used the release wax. This time to prevent stray fibres I used a paintbrush to apply the wax and a micro fibre cloth for polishing. This worked better as there was less fibre on the mould but it was still dull looking. I also applied several coats instead of just two.

I left the other mould free from any release agent, so the resin had direct contact with the rubber itself.

I also used two brass rods in each cast for the supports to help make it more stable once placed in the box.

Unfortunately, I had exactly the same problems on both moulds, the exposed surface cured perfectly and the unexposed surfaces had a few millimetres of not fully cured resin that were quite tacky to the touch.

Interaction Design: Resin Phase Introduction (part 4)

Interaction Design: Resin Phase First Attempt (part 2)

Interaction Design: Resin Phase Introduction (part 1)

I applied the release wax to the first mould I made. The instructions said to apply several coats, polish each coat to a shine and wait for 10 to 20 minutes between coats. Then leave for two hours to dry. I couldn’t get the couple of coats I applied to shine and was instead left with a dull looking surface that had bits of the soft cloth I was using stuck to the mould. So I washed the mould out with hot soapy water and then left it to dry before I poured the resin in. I left the resin to set for around 12 hours and discovered the sticky surfaces when I released it from the mould. Leaving it out in the air for a night didn’t help the surfaces to set and they remained sticky. I had only used a single brass rod to support this cast which was not sturdy enough, and with the sticky surfaces, I decided to try again.

Interaction Design: Resin Phase Introduction (part 3)