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Top 5 Most Common Problems with Hand Casting Kits, How To Avoid Them and How to Fix Them

We think it’s really important that you have an idea of what the most common problems with hand casting kits are before you commit to buying one. You love the idea of making a cast but are worried about what might go wrong. When you’re searching online for hand casting kits, all you see are perfect results and claims from sellers about how easy their kits are to use.

You may be particularly worried because you want to make a casting to mark a special occasion. This might be a wedding or a special anniversary. Or you might need to make a cast with a loved one who is elderly or very unwell. Sometimes you only get one shot at making this lasting memory so you want to be sure it’s going to work.

We know it can be hard to find information about what might go wrong, so here we’re going to explain the top 5 most common problems with hand casting kits and how to avoid them (or fix them!).

Problem 1. Casting Gel Sets Too Quickly

Occasionally we hear from customers who haven’t been able to get their hands into the bucket before the casting mixture (alginate) has started to set. That is obviously super frustrating so here are our top tips.

How to Avoid Your Gel Setting Too Quickly

Temperature Alginate sets more quickly when the water or room temperature is warmer, so use cold water from the tap to give yourself as much time as possible to get it mixed.  Using cold water will mean you need to keep still for longer so make sure you find a really comfortable position to hold before you start mixing. If possible, avoid making your casting on any particularly hot days!

Mixing You should always use an electric mixer as getting our premium alginate mixed with a hand whisk or a wooden spoon is going to be incredibly difficult before it starts to set.

Get Help Get a friend or family member to pour in the bags of alginate while you mix, this will mean you can just keep mixing and will save you time.

Adding the Alginate Add half a bag of alginate at a time and mix it fairly slowly until it’s just absorbed into the water before adding the next half bag. Once all the alginate powder is absorbed, turn up the electric mixer to full speed and mix until smooth.  You can see our video demonstrations here:

Mixing Alginate – Edinburgh Casting Studio Couple Kit

Mixing Alginate – Edinburgh Casting Studio Family Kit

How to Fix It

If you’ve used one of our kits and followed all of our top tips but still didn’t manage to get it mixed in time, get in touch by emailing us at hello@edinburghcasting.com or call our friendly team on 020 7064 5177. We can send you more alginate to have a second attempt.

A Note About Other Kits

Our kits include quick setting alginate because this type of alginate captures the best detail of your hands, including jewellery. Some kits that we have tested use lower quality slow-setting alginate. While this gives you plenty of time to get it mixed and get your hands in the bucket, just remember that you may have to stay in position for up to 10 minutes! This is surprisingly hard to do and can be really uncomfortable even for able-bodied people and almost impossible for for younger children or elderly/frail relatives.

Just be aware that the longer you have to hold still and the more uncomfortable you become, the more you will end up moving your hands and this will result in a poor cast with lost detail like this:

Lost detail due to movement during casting

Problem 2. Bubbles on the Skin Surface

A very common problem with hand casting kits are the appearance of unwanted small or even larger bubbles on the surface of your cast like this:

Air bubbles on skin surface

These bubbles are caused by air getting trapped in the alginate during mixing.

How to Avoid Bubbles on the Skin Surface

Mixing Make sure that the alginate is mixed as thoroughly and smoothly as possible. As explained above, you can use colder water to allow yourself extra time to get it thoroughly mixed to eradicate any bubbles.

How to Fix It

You can carefully scrape away tiny bubbles using a suitable tool. Don’t try and flick them off as this will result in little craters on the skin surface. Our kits come with a wooden tool that can be used for small bubbles or you can use a craft knife or scalpel.

You should remove larger bubbles by gradually scraping them off. Do this carefully layer by layer until you reach the level of the skin surface. A craft knife or scalpel is best for this.

Watch our video demonstration here:

Problem 3: Lost Fingertips

One of the most upsetting problems with hand casting kits occurs when air gets trapped in the fingertips in the mould that you’ve created. When this happens the liquid stone mixture won’t be able to reach the tips so you can end up with a cast that looks like this:

Lost fingertips during casting

How to Avoid Losing Fingertips

Hand Position Make sure that fingertips are in contact with the other hand when you form the shape you’re going to dunk into the bucket. Fingertips that are ‘floating’ as shown below are hard to fill with the stone:

Plaster Pour To avoid getting air trapped in fingertips make sure you hold the mould at an angle when you first pour in the liquid stone, as shown below:

As an extra precaution, first just fill up to the fingertips, rotate the bucket to ensure the fingers are all coated, then tip the plaster back out into the bowl before filling your mould as instructed in the booklet.

How to Fix It

Just in case you still lose some fingertips, we recommend holding back a bit of stone powder before mixing it up so you can make repairs as shown in our demonstration here:

Problem 4: Holes or Channels in the Skin Surface

It’s not unusual to have some tiny holes in the surface of the skin like those shown here:

Holes in skin surface

These are caused by tiny air bubbles getting trapped in the stone liquid.

Occasionally, you may even have channels in the plaster like this:

Water channels in skin surface

These are caused by water separating from the stone powder during the setting process.

How to Avoid Holes or Channels in the Skin Surface

Mixing If you don’t spend enough time thoroughly mixing your stone it may start to separate during the pour. Make sure it’s thoroughly mixed for about 5 minutes until you’ve removed all lumps and it’s starting to slightly thicken.

Tapping You must keep tapping the bucket during the stone pour to release air from the liquid stone. Keep tapping at every stage of the pour and after you’ve filled the mould up to the top of the wrists. Take it in turns if it gets tiring, but try to keep tapping both sides of the bucket until the liquid stone starts to thicken and then stop. This will bring all the bubbles to the surface and prevent the liquid stone from separating and forming channels.

How to Fix It

Hold back some of your stone powder (just a couple of spoonfuls) in case you need to make some repairs. Mix equal parts of stone powder to water, then you can fill in the holes and channels as shown in our video demonstrations here:

Problem 5: Black Dots Appearing on the Surface

Very occasionally we hear from customers who have started to see little black dots appearing on their hand casts in the days after making them. This is rare, but obviously upsetting if you think your cast is ruined, so here are our top tips:

How to Avoid Black Spots Appearing on your Hand Cast

Make sure you dry your cast out in a well-ventilated, dry place, ideally on a cooling rack (the type you use for baking). In cold weather, if you can put it next to a radiator that is ideal. Make sure air can flow all around the cast and turn it from time to time so that the base gets exposed as well.

How to Fix It

Apply a dab of slightly diluted bleach to the little spots using a cotton bud or white tissue. These should disappear very quickly.

Once the spots have been removed, place your casting in a dry and well-ventilated space to dry for a further week.

If You Need More Help

We hope we have clearly explained all of the most common problems with hand casting kits here. If you follow all of our top tips and watch our videos, you should have a really positive hand casting experience! However, if you’ve used one of our kits and anything else goes wrong just give our award-winning customer care team a call on 020 7064 5177 or send us an email to hello@edinburghcasting.com and we’ll do everything we can to help. We’re here to hold your hand!



46 Responses

  1. Please can you tell me what to put on my couple hands that I made to seal it as there wasn’t any seal included in my box and what make of fluid acrylic paint to buy as I want it bronze with the black line detail so what make of wax do I need too thank you

    1. Hi Paula

      Sorry for the delay in getting back to you! You need to use diluted PVA glue to seal your cast once it has fully dried out. Dilute the glue 1 part to 4 parts water, then lightly brush all over the surface.

      The best paint to use is fluid acrylic paint – we recommend Golden as a brand. The effect that you’re after is created by painting with a dark bronze colour first (bronze + black) then using a special effects wax over the surface. We recommend Rub’n’Buff as a brand.

      We hope that helps!

      1. I made my kit 4 days ago, however it’s flaking and gathering a lot of white powder on top. Looks like mold, but it’s not mold. When you blow on it it Flys off. Almost like dust. Anyone know the cause and how to stop this?

        1. Hi Luise

          This is not unusual. As moisture in the stone dries, it can form crystals on the surface. Don’t try to brush them off for another couple of weeks as this may take away some of the skin detail on your cast. Once it has fully dried, you can then gently brush them away.

          We hope that helps!

      2. Hii can u suggest me is it compulsory to use sealent for baby casting? If yes ,can u suggest me which sealant is best and after using sealant can I use acrylic spray paint? How many coats should I apply after sealed

        1. Hi Deepa

          No, it’s not essential, but it does protect the surface. If you are going to paint the casts, you should definitely seal the them first. We recommend diluted PVA glue. We don’t recommend using spray paint as it can be hard to control and you may obscure the skin detail. We apply professional quality fluid acrylic paint with a paintbrush.

          We hope that helps.

    2. After applying pva glue how long should I leave to get dry and how many coats should I apply paint for cast. Another question can I use primer instead of pva glue ?

  2. What is pva glue! Is it possible to use a water-based or oil-based paint for the cast?
    Why do nails break after opening the cast, and is there a way to preserve the nails?

    1. PVA glue is a water-based adhesive and can sometimes be known as wood glue, carpenter’s glue or in the US, Elmer’s glue.

      The paint that we recommend for use on casts is water-based fluid acrylic. It’s important not to use a paint that’s too thick as this will cover the skin detail.

      Nails can be very difficult to cast because they are obviously thin and therefore fragile, so can easily snap off when you remove the cast from the alginate mould. However, if you can retrieve them from the mould they can be stuck back on with superglue. We hope that helps.

  3. Hi ,
    I have done the cast with my parents today. Just wondering can I keep the casting mix in the mould for more than 24 hours as I am flying back home in the another 12 hours and don’t want to ruin or get wet hand cast due to time shortage. Please help me if I can take the entire mould cast which is done today as is and remove it when I reach home in 24 hours, many thanks

    1. Hi Dia

      I just picked up your question.

      We wouldn’t recommend leaving the cast for that long before removing it from the mould.

      It needs to be removed to start drying out otherwise the moisture inside the stone can start to form mold spores on the surface of the cast.

      It would be better to take it out of the mould now, put it somewhere really warm to dry out then wrap it up carefully in bubble wrap and take it with you.

      We hope that helps


  4. I have done the cast with my parents today. Just wondering can I keep the casting mix in the mould for more than 24 hours as I am flying back home in the another 12 hours and don’t want to ruin or get wet hand cast due to time shortage. Please help me if I can take the entire mould cast which is done today as is and remove it when I reach home in 24 hours, many thanks

    1. Hi Dia

      I just picked up your question.

      We wouldn’t recommend leaving the cast for that long before removing it from the mould.

      It needs to be removed to start drying out otherwise the moisture inside the stone can start to form mold spores on the surface of the cast.

      It would be better to take it out of the mould now, put it somewhere really warm to dry out then wrap it up carefully in bubble wrap and take it with you.

      We hope that helps


  5. Hi. I have a beautiful cast waiting to dry it has one more week before i seal it. But ive found it has what looks like frosting on it.. Every morning i brush it off but there the next day.. Can i seal it before the 2 weeks? Will it effect it?
    Thanx Elaine

    1. Hi Elaine

      The frosting that you describe is actually crystals that are part of the drying process. We suggest you leave the cast for a couple of weeks without brushing it as that may remove some of the skin detail. After a couple of weeks, just brush it off and then you can seal it.

  6. Good morning

    My question us, do you seal a cast with PVA glue even if you’re painting it? Or is the seal just for keeping the hands the plaster colour?

    What are the correct steps to take after removing the cast from the alginate?

    I am hoping to paint them gold. Thank you

    1. This is a great question. We suggest you wait for two weeks from completion of the cast before sealing with the diluted PVA. Allow that to dry, then apply the paint.

      We recommend fluid acrylic paint, which doesn’t cover up the skin detail.

      Hope that helps!

  7. My hand mold with my kids came out great. However, I cannot get it to stand up straight on its stand. It just keeps leaning. What can I do to make it stand up straight. I cannot shave the bottom because it will just keep leaning that way.

    1. We’re sorry to hear that you’ve got a leaning handcast. The angle of the hands can be hard to predict, but is usually caused by the hands entering the mixture at an angle. It’s not a big problem though, and we can certainly help you work out a way to stand it up.

      Usually, when making a piece myself, I’d actually saw the casting to the correct angle, however this isn’t something I’d recommend you attempt.

      The best way to make your cast stand up would be by gluing the piece to a base. My first recommendation would be to use a wooden base. This is much easier for a glue to stick to, as it has a rough texture with plenty of natural imperfections in the grain of the wood.

      You will need to ensure the base of your casting is flat, so sandpaper is best for this (only sand the base gently by hand, and do not sand the skin texture)

      You can find affordable wooden bases at trophy parts suppliers, or on eBay. Once you have ensured the casting will grip the base well (good contact between the casting and plinth) use a strong epoxy glue. This is what professional framers use.

      You should only glue your piece once it’s completely dry, and sealed as per the instructions. It is best not to screw into the casting, as it is like screwing into a plaster wall- it won’t grip, it will only shear a hole in the plaster that the screw will loosely turn in.

      I hope this is helpful.

      Warm wishes


  8. Hi I had a kit bought for me for Xmas
    I like the cast in its natural state so I have to paint it ?
    I was thinking of sealing and just light dusting with bronze powder to pick out details
    Will this work

    1. Hi Sarah

      If you like the natural state, we suggest you just seal it once it has fully dried out (we suggest waiting for two weeks after the casting).

      In terms of dusting with bronze powder, this isn’t something that we have tried and can’t imagine that dust would adhere to the surface once the cast has dried. As such, we can’t recommend this I’m afraid.

      With best wishes


    2. Hii can u pls suggest which brand is good for pva glue I’m not getting pva glue in my place is their any other name of pva glue and what are the advantages of pva glue

      1. Hi

        Any diluted PVA glue would work fine. Another name for this is wood glue. This seals the cast and protects the surface. Did you make your cast using one of our kits? We can’t offer specific advice for casts made using other branded materials.



  9. Hello. I want to get this for a gift as a memory for a family in which the dad is terminal. Because of how poorly he is he is very shaky. Am I right in thinking this isn’t going to work with this?

    1. Hi Lauren

      We’re very sorry to hear about this sad situation. This is such a lovely idea but you’re right, shaking can be an issue. However, because his hand will be held by another hand, it may be enough to keep him still for the 2-3 minutes it takes for the casting jelly to set.

      We know that other families have managed to make these all-important casts in similar situations, so it may well be worth a try.

      We hope that helps.


  10. Have you ever tried to place one of these in oven on low heat periodically to speed up the drying process of you don’t have 14 days to wait?

    Thank you!

    1. Hi Kelly

      This is a great question. We would advise against putting your handcast in the oven, as this may cause it to crack. If you put it in an airing cupboard or above a radiator, a week should be long enough to dry it out if it’s a two-hand cast.

      We hope this helps.


  11. I have a cast that had a piece break during us moving. Is there a specific superglue you recommend to use to put it together?

    1. Sorry to hear about your breakage. You can use household superglue or a two part epoxy glue to make repairs. You can then cover any little cracks with some stone plaster mixed with water.

      We hope that helps!

  12. Hey hello

    I m facing some colour bleedings problem in my cast as my golden colour starts turning into black after putting my cast into frame after few days..

    1. Hi

      We’re sorry to hear you’re having trouble with your cast. Can we check if you made your cast with an Edinburgh Casting Studio kit and what type of paint you used?


  13. I have a question completely unrelated to CREATING a cast, but actually about aftercare! My son died at 16 months old from childhood cancer back in 2009. They casted his hands for me right before he passed. I stupidly never put them in any sort of display case to protect them and now they’re quite yellowed and dirty. Is there anything I can do to clean them without destroying them altogether?

  14. Whilst touching up the casting, removing bubbles etc some areas on the fingertips and top of the knuckles got slightly soiled from handling the cast. Would it be ok to add white acrylic paint to the PVA fixing solution to cover up these areas or just paint the white on after the fixing solution has dried.

    1. Dear Ellen

      This is a great question. We wouldn’t recommend adding paint to the PVA solution. Your best option is to paint it either with diluted white acrylic (water-based) or even better, a white spray paint. We recommend this white primer which is matte and doesn’t cover the skin detail: https://www.toolstation.com/zinsser-b-i-n-primer-sealer-spray-paint/p95263

      Make sure you spray from a distance with sweeping motions – you don’t want to apply too much in one place.

      We hope that helps!

  15. I have a hand mould of my dad who passed. Unfortunately it has been taken at an angle and when I poured in the plaster it has left a hard base. Is there anyway I can cut this away from the hand without any damage or smooth it down so the base looks even. Thank you.

    1. Hi Julie

      We’re so sorry to hear about your dad. The best way to remove the base would be with a bandsaw but we don’t suggest you try this yourself. If you can send us an email to hello@edinburghcasting.com we can help you resolve this.

      Best wishes


  16. Hi, I wanted to make a cast of my grandma’s hands. I dont live by her and I know the plaster takes at least 4 hrs to set. I have a 2 hr drive home can I make a mold of her hands with the alginate then when I get home pour the plaster in? Or do I have to put the plaster in right after molding her hands and if so would the wet plaster set right on the drive home? This is my first one so I’m not sure 🙂

    Thank you

    1. Hi Briana

      You can certainly make the mould first then take it home and pour the plaster. We suggest you don’t leave it overnight, but do it within a few hours of making the mould with her.

      Best wishes


  17. Hey.I accidentally painted the casting with metallic acrylic paint and put them in a frame.I didn’t sealed them.does it effect my casting ?

    1. Hi there

      I’m afraid there is a chance that the paint might start to flake because you haven’t primed/sealed the plaster first. We do hope that isn’t the case! If that does happen, the only thing you can do is touch it up with more of the paint.

      Sorry we can’t be of more help, but good luck.


      Best wishes


  18. Hi Alex
    I think we didn’t mix the alginate for long enough and now our hands are literally covered in bubbles. Should I wait until the hands have completely dried out or try and remove them straightaway?

    1. Hi Corrine

      Sorry to hear you have a lot of bubbles and sorry for the delay in getting back to you. You can remove them at any time – just use the technique shown in our handy video in the blog. Use a craft or stanley knife and make sure you don’t flick them as this can leave little craters on the surface. You want to scrape them off gently.

      We hope that helps.


  19. Hi, I was wondering if you could answer my random question please. I took a casting of my mums hand when she passed. I’d like to now get my children’s hands holding the cast and re cast it (if that makes sense) so that it looks like they are holding her hand, however I’m nervous, if I get the children to hold the casting and put it in the tub with alginate will the plaster of paris casting ruin? Or will it work like a normal ‘hand’ in there.

    1. Hi Linzi

      We’re very sorry to hear about your mum and completely understand why you want to make this precious cast with your children. It is possible, but there is a risk that it might not turn out well and you will have lost the original cast in the process. For this reason, we’d strongly suggest you have a duplicate made of your mum’s hand so you have the original and can try this casting with the copy.

      Unfortunately, it’s not possible to make a duplicate yourself as this requires professional expertise and different materials (it can’t be done with one of our kits). We do offer a duplication service so do email us at hello@edinburghcasting.com if you would like to look into this.

      Warm wishes


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